Acute posthemorrhagic anemia in adults: a review

Acute posthemorrhagic anemia is anemia that develops following a rapid, acute episode of blood loss: trauma, gastrointestinal bleeding, obstetric hemorrhage, rupture of a vascular structure, or postoperative blood leak. The key mechanism is a sudden decrease in circulating red blood cell mass and oxygen carrying capacity, leading to tissue hypoxia and compensatory responses from the cardiovascular and respiratory systems. In the first hours, the hematological "picture" can be misleading due to hemodilution that has not yet occurred: hemoglobin and hematocrit do not decrease immediately, but rather as fluid moves into the vascular bed and infusion therapy occurs. [1]

Clinically, the condition varies from mild weakness and tachycardia to hemorrhagic shock and multiple organ failure. The source of bleeding determines the tactics: for example, in case of upper gastrointestinal bleeding, endoscopy and proton pump inhibitors are used; in case of trauma, surgical hemostasis, interventional radiology, and sometimes, reversible balloon occlusion of the aorta (REBOA) in experienced centers; in case of postpartum hemorrhage, uterotonics, tranexamic acid, mechanical and surgical methods are used. [2]

The diagnosis of acute posthemorrhagic anemia is important not in itself, but as a marker of a serious event—acute blood loss. Therefore, the physician's goals are: 1) to stop the bleeding; 2) to stabilize hemodynamics and oxygen delivery; 3) to replenish blood and clotting factors using damage-control resuscitation principles; 4) to prevent relapse and iron deficiency after stabilization. Physiological restoration of erythropoiesis begins with a delay of approximately 3-4 days: then reticulocytosis increases, "catching up" with the loss of red blood cells. [3]

Even after blood loss has been controlled, patients face a period of "aftereffects": iron deficiency and fatigue, rehabilitation, and correction of risk factors for rebleeding (anticoagulants, peptic ulcer disease, portal hypertension, obstetric factors). Here, "patient blood management" strategies come to the fore: restrictive transfusion thresholds, early administration of intravenous iron, rational imaging, and careful laboratory sampling tactics. [4]

Code according to ICD-10 and ICD-11

In ICD-10, the code D62 is used for acute posthemorrhagic anemia. This is a billable and specific code; the note "Excludes: anemia due to chronic blood loss (D50.0)" helps distinguish between acute and chronic cases. In combination, both the cause of bleeding (e.g., gastrointestinal bleeding or ulcer) and the anemia itself are often coded as D62. [5]

ICD-11 does not have a direct entry for "acute posthemorrhagic anemia" as in ICD-10; the practical approach is to code "Iron deficiency anemia" (3A00) with post-coordination of the cause (acute bleeding) and the localization/condition (e.g., postpartum hemorrhage) or to use the corresponding codes for the causative condition under the chapters on trauma, digestive diseases, and obstetric conditions. For chronic posthemorrhagic anemia, there is a subsidiary code 3A00.01. [6]

Table 1. Frequently used codes

Situation	Classification	Code	Comment
Acute posthemorrhagic anemia	ICD-10	D62	The main diagnosis of anemia in acute blood loss. [7]
Iron deficiency anemia (ICD-11)	ICD-11	3A00	The cause (acute bleeding) is indicated by post-coordination. [8]
Chronic posthemorrhagic anemia	ICD-11	3A00.01	Long-term blood loss (eg, colon tumor). [9]
Upper gastrointestinal bleeding	ICD-10	related codes (e.g. K92.2)	Often coded together with D62. [10]

Epidemiology

Acute blood loss is one of the leading causes of preventable death in trauma: it is estimated that bleeding causes over 60,000 deaths in the United States and up to 1,500,000 worldwide annually; the proportion of hemorrhage as a cause of preventable death in some studies reaches 30-40%. This explains why components of damage-control resuscitation and early hemostasis have become the standard. [11]

Gastrointestinal bleeding is a common trigger for acute anemia in adults. The incidence of upper gastrointestinal bleeding is estimated at 80-150 cases per 100,000 population per year, with a mortality rate of 2-10% depending on age and comorbidities. Hospitalizations amount to hundreds of thousands per year, with men being more frequently affected. [12]

Obstetrics: Postpartum hemorrhage remains the leading cause of maternal mortality worldwide, accounting for approximately 20% of maternal deaths and approximately 70,000 deaths annually; prevalence, according to surveys, ranges from 3% to 10% and higher, with significant regional variations. This is a critical contributor to the burden of acute posthemorrhagic anemia in women. [13]

Hospital-acquired anemia is also common in hospitals due to diagnostic phlebotomies, procedures, and blood loss: according to reviews, 40-74% of patients are discharged with anemia, which worsens outcomes and increases the risk of transfusions during subsequent interventions. This reinforces the importance of careful laboratory management. [14]

Table 2. Epidemiological landmarks

Indicator	Grade
Mortality from traumatic hemorrhage (world)	≈ 1,500,000 per year
The contribution of hemorrhage to preventable mortality in trauma	30-40%
Upper gastrointestinal bleeding: incidence	80-150 per 100,000 per year
Postpartum hemorrhage: contribution to maternal mortality	≥20%

Reasons

The main clinical "sources": 1) trauma (ruptures of parenchymal organs, vascular damage); 2) gastrointestinal bleeding (ulcers, erosions, portal hypertension, tumors); 3) obstetric and gynecological bleeding (uterine atony, obstetric pathologies of the placenta, ruptures); 4) postoperative blood loss (range from small to massive). Each of the scenarios dictates its own hemostasis algorithms. [15]

Medications exacerbate blood loss, including anticoagulants, antiplatelet agents, nonsteroidal anti-inflammatory drugs, and glucocorticosteroids. In the elderly, the combination of peptic ulcer disease and anticoagulant use is a common cause of severe bleeding, especially in the presence of renal and hepatic dysfunction. [16]

Less commonly, the source is vascular malformations, ruptured aneurysms, tumor invasion of blood vessels, and complications of invasive procedures (biopsies, endoscopy, angiography). In some cases, blood loss remains "hidden" (retroperitoneal, intramuscular bleeding) and requires active visualization (computed tomography angiography). [17]

Finally, the contribution of “iatrogenic” blood loss (frequent blood draws, large tubes in low-weight patients) is economically and clinically significant and should be taken into account in intensive care units and postoperative beds. [18]

Risk factors

Age and comorbidities (cirrhosis, chronic kidney disease, cardiovascular disease) increase the risk of both bleeding itself and an adverse outcome with the same amount of blood loss. The presence of portal hypertension is a marker for possible variceal bleeding, which requires a different approach than non-variceal ulcers. [19]

Taking anticoagulants and antiplatelet agents increases the risk and severity of bleeding; management of these drugs in the acute phase should be protocol-based: temporary discontinuation, antidotes (where available), and a measured reintroduction after hemostasis. Guidelines recommend against platelet transfusion "just in case" for antiplatelet-associated bleeding without thrombocytopenia. [20]

Obstetric risk factors for postpartum hemorrhage include uterine atony, placental abnormalities, multiple pregnancy, macrosomia, and hypertensive disorders of pregnancy. These factors influence the prevention and preparedness for massive transfusion. [21]

Hospital factors: high phlebotomy volume, prolonged ventilation, sepsis, dilution/consumption coagulopathy. Reducing "diagnostic" blood loss is part of patient blood management programs. [22]

Pathogenesis

In the first minutes to hours, volume loss is critical: preload, cardiac output, and oxygen delivery all fall. The body responds with tachycardia, peripheral vasoconstriction, and catecholamine release. With continued blood loss, hypoperfusion and lactic acidosis develop.

As interstitial fluid moves into the vascular bed and is infused, hemodilution occurs: hemoglobin concentration and hematocrit decrease, which masks the real moment of blood loss if you look only at the labs “right now.”

After 3-4 days, the bone marrow "gets going," and reticulocytosis—a sign of regeneration—occurs. This "delay" explains why early reticulocytosis isn't always detected within the first 24 hours, whereas it's expected by days 3-7. Subsequently, reticulocytosis subsides as red blood cell mass recovers. [23]

If blood loss is significant, iron deficiency is almost inevitable, which cannot be corrected by transfusion alone; iron replacement, usually intravenous, is required to quickly close the deficiency and reduce the need for donor blood. [24]

Symptoms

Classic signs include sudden weakness, dizziness, blurred vision, tinnitus, cold sweat, and thirst. Objectively, these include tachycardia, hypotension, cold extremities, and pale skin and mucous membranes. In cases of massive blood loss, signs of organ hypoperfusion include confusion, oligo-/anuria, and lactic acidosis.

Local symptoms depend on the source: melena, "coffee grounds" or hematemesis with upper gastrointestinal bleeding; hematochezia with lower bleeding; pain and tension in the abdomen with intra-abdominal bleeding; postpartum - profuse bloody discharge, soft "atonic" uterus. [25]

Laboratory tests may show "normal" hemoglobin levels in the first few hours, but lactate and base deficit levels increase, and signs of dilutional coagulopathy appear with massive infusions. Over time, hemoglobin and hematocrit decrease, and later, reticulocytosis increases. [26]

Special signs of severity: intractable hypotension, increasing tachycardia, signs of ongoing blood loss (heavy discharge, frequent filling of canisters, repeated melena, a drop in hemoglobin >20 g/l over 6-12 hours), as well as clinical signs of intracavitary bleeding without an external source.

Classification, forms and stages

The clinic uses functional stratification of blood loss (by percentage of blood volume, shock) and source (trauma, gastrointestinal, obstetric, postoperative). For gastrointestinal bleeding, a distinction is made between varicose and non-varicose types, which determine medications and the timing of endoscopy. [27]

The severity of shock is assessed based on changes in heart rate, blood pressure, consciousness, urine output, and lactate levels. In trauma, the concepts of "massive transfusion" and "intractable bleeding" are widely used—indications for the "massive transfusion protocol" and "damage-control" approaches. [28]

In obstetrics, blood loss volume thresholds (≥500 ml after vaginal delivery or ≥1000 ml after cesarean section with signs of hypovolemia) have been adopted, which helps standardize the team's response and the initiation of protocols. [29]

Table 3. Practical “classification” of clinical situations

Axis	Categories	How does it affect tactics?
Source	Trauma / Gastrointestinal / Obstetrics / Postoperative	Selecting a hemostasis method and team
Heaviness	Without shock / Compensated / Decompensated shock	Are MTP, resuscitation, REBOA necessary?
Type of gastrointestinal bleeding	Varicose / Non-varicose	Drugs and timing of endoscopy
The course of bleeding	Stopped / Ongoing / Relapse	Repeat endoscopy, embolization, surgery

Complications and consequences

The main early complications are hemorrhagic shock, dilution and consumption coagulopathy, hypothermia, and acidosis, leading to the "lethal triad." The risks of organ ischemia, acute renal failure, cardiac dysfunction, and neurological outcomes increase.

In gastrointestinal sources, there is recurrent bleeding, infection, and the need for repeat endoscopy or angioembolization; in varicose veins, there is a risk of liver decompensation. In obstetrics, there is a need for massive transfusions, hysterectomy, and lactation and psychological consequences. [30]

Transfusions are life-saving, but they carry risks: volume overload, transfusion-associated acute respiratory failure (TARF), alloimmunization, infections (extremely rare), hypocalcemia, and hypokalemia with massive infusions. Therefore, current guidelines promote restrictive transfusion thresholds and "targeted" correction based on TEG/ROTEM data. [31]

In the long term, posthemorrhagic iron deficiency, weakness, and decreased performance are common. In these cases, intravenous iron allows for faster restoration of hemoglobin and ferritin stores, reducing the need for donor red blood cells in future interventions. [32]

When to see a doctor

Immediately - if you experience signs of active bleeding (melena, "coffee ground" vomiting, bright blood from the rectum, heavy bleeding after childbirth), sudden weakness, fainting, abdominal pain, increasing pallor, and shortness of breath. These symptoms require calling an ambulance.

Urgently - when taking anticoagulants/antiplatelet agents against the background of any signs of bleeding, with cirrhosis and suspected variceal bleeding (such patients require endoscopy and therapy in the first 12 hours after stabilization). [33]

Planned - after discharge from the hospital to monitor iron, ferritin and hemoglobin, discuss the prevention of relapse and discontinuation/resumption of antithrombotic therapy.

Immediately repeat - if symptoms recur, hemoglobin levels drop in home tests, black stool or bright blood appears, as well as if fever and shortness of breath occur after recent transfusions (suspected transfusion complications).

Diagnostics

Step 1. Clinic and basic lab. Assess vital signs, shock scales, and establish two large intravenous lines. Immediately obtain a complete blood count, blood type and Rh factor, antibody screen, coagulation profile, fibrinogen, lactate, and blood gas analysis. Be aware of "false normal" hemoglobin levels before hemodilution in the first few hours. [34]

Step 2. Search for the source. If upper gastrointestinal bleeding is suspected, an early consultation with an endoscopist and endoscopy should be performed within 24 hours of stabilization (or, in the case of variceal bleeding, as soon as possible after stabilization, typically within 12 hours). Early administration of erythromycin before endoscopy improves visualization; after hemostasis, high-dose proton pump inhibitors should be administered. [35]

Step 3. Imaging in case of doubt/failure of endoscopy. In case of ongoing or occult bleeding, use computed tomography angiography as a first step to localize the source and plan embolization; in case of negative endoscopy and intermittent bleeding, radionuclide scanning with labeled red blood cells (sensitive to low rates of blood loss) is helpful. [36]

Step 4. Spot hemostasis tests. In cases of massive blood loss and coagulopathy, rely not only on the standard coagulogram, but also on viscoelastic tests (TEG/ROTEM) - they speed up decision-making regarding plasma, cryoprecipitate, and platelets and improve the targeted nature of correction. [37]

Table 4. A set of primary studies for suspected acute posthemorrhagic anemia

Block	What to do	For what
Laboratory	Complete blood count, blood type/Rhesus factor, antibody screening, INR/APTT, fibrinogen, lactate, gases	Assessment of anemia, preparation for transfusion, identification of coagulopathy
Endoscopy	EGD ≤24 hours (varicose veins - as soon as possible ≤12 hours after stabilization)	Diagnostics and hemostasis
Visualization	CTA in case of doubt/active bleeding; red blood cell scintigraphy in case of intermittent bleeding	Localization of the source, embolization plan
VET (TAG/ROTEM)	As indicated in cases of massive blood loss	Targeted correction of hemostasis

Differential diagnosis

Acute "anemia" can be: 1) hemolytic (jaundice, elevated indirect bilirubin, high lactate dehydrogenase, reticulocytosis "without delay"); 2) dilution (intensive infusions without an obvious source of bleeding); 3) acute bone marrow suppression (reticulocytes are low, pancytopenia is possible).

Distinguish between variceal and non-variceal gastrointestinal bleeding—these require different treatment algorithms and endoscopy timeframes. Also, consider the potential for "false negative" early laboratory results in a patient with ongoing bleeding: clinical findings are more important than initial results. [38]

If the source is not found by standard endoscopy, follow the route: CTA → angiography with embolization if confirmed → if CTA is negative and there is intermittent bleeding, RBC scintigraphy or capsule endoscopy/enteroscopy for the small bowel. [39]

Be especially mindful of “hospital-acquired anemia” in intensive care patients due to phlebotomies – here, treatment is not about finding a “super-source,” but about limiting diagnostic blood loss and iron-sparing strategies. [40]

Treatment

They begin with a parallel two-circuit approach: 1) stopping bleeding (endoscopy, surgery, interventional radiology, obstetric tactics); 2) resuscitation based on damage-control principles: if there are signs of massive blood loss, a rapid initiation of a massive transfusion protocol with empirical ratios of red blood cells, plasma and platelets and priority on the availability of blood units "here and now" (including low-titer "O-whole blood", where available). Early correction of calcium, prevention of hypothermia, and timely use of tranexamic acid in the first hours of injury are supported. [41]

Red blood cell transfusions are currently performed using a restrictive strategy: in hemodynamically stable adults, transfusion is considered when hemoglobin levels are below 70 g/L; for certain categories (ischemic heart disease, cardiac surgery), the threshold may be higher on a case-by-case basis. The key is to focus not only on the hemoglobin level but also on the clinical manifestations of hypoxia and bleeding activity. This approach reduces unnecessary transfusions without worsening outcomes. [42]

For upper gastrointestinal bleeding, endoscopy within 24 hours of stabilization is the standard, and "excessive urgency" (≤12 hours) for non-variceal bleeding generally does not improve outcomes and may be harmful if resuscitation is incomplete. After endohemostasis, high-dose proton pump inhibitors (continuous or intermittent for 3 days) and then oral regimens are indicated; in case of recurrence, repeat endoscopy; if unsuccessful, transcatheter arterial embolization is the preferred option in fragile patients. [43]

Interventional radiology plays a key role when endoscopy is unavailable/ineffective or the source is lower. Computed tomography angiography helps quickly localize bleeding, and angioembolization provides high technical and clinical success, although the risk of ischemia increases with lower bleeding, so a more balanced approach is required. If angiogram is negative, "empirical" embolization is acceptable in carefully selected patients. [44]

Tranexamic acid is effective in trauma patients when administered as early as possible (preferably a 2 g bolus with a "window" of up to 3 hours after injury, according to updates). In obstetrics, tranexamic acid is used as part of a comprehensive treatment regimen for postpartum hemorrhage. The decision regarding its use outside of trauma and obstetrics is made on an individual basis (discussions regarding its benefits for gastrointestinal bleeding are ongoing). [45]

REBOA (Balloon Endovascular Aortic Occlusion) is a specialized option for non-compressible torsional bleeding and traumatic circulatory arrest in experienced centers: it may provide time until surgical hemostasis, but requires rigorous selection, protocols, and training; studies show mixed results on survival and complication risk, so the technique remains "niche". [46]

In obstetrics, the algorithm includes uterotonics, manual and mechanical methods (balloon tamponade), tranexamic acid, correction of coagulopathy and readiness for massive transfusion; in case of refractory bleeding - uterine artery embolization or surgical methods (vascular ligation, hysterectomy). After stabilization - mandatory iron correction (oral or intravenous depending on severity). [47]

Once blood loss has been controlled, iron replacement should be performed. Randomized and synthetic reviews show that intravenous iron (eg, ferricarboxymaltose or derisomaltose) normalizes hemoglobin and ferritin stores more rapidly after gastrointestinal bleeding than oral salts and is preferred in moderate/severe anemia, intolerance to oral iron, and the need for rapid recovery. This is part of a strategy to reduce repeat transfusions. [48]

Viscoelastic management (TEG/ROTEM) facilitates the administration of plasma, cryoprecipitate, and platelets "on demand" rather than "by eye," reducing the time to correction and blood products. Recent reviews emphasize that the use of these technologies in trauma and critical care accelerates and refines decisions, although it requires the implementation of protocols and staff training. [49]

Finally, patient blood management: minimizing phlebotomies, using microtubes, revising thresholds for elective procedures, timely discontinuation and subsequent balanced reintroduction of antiplatelet and anticoagulant medications, nutritional support, and rehabilitation. Such systematic work reduces the risk of hospital-acquired anemia and decreases dependence on donor blood. [50]

Table 5. Restrictive thresholds for red blood cell transfusion (guidelines)

Situation	Recommendation
Hemodynamically stable adults	Consider transfusion if Hb < 70 g/L
Concomitant ischemic heart disease/special situations	Individually (often 70-80 g/l)
Expected/ongoing blood loss	The clinic is more important than the numbers; decide dynamically

Table 6. Hemostasis tools for gastrointestinal bleeding

Stage	Tool	The essence
Endoscopy	Hemoclips, thermocoagulation, injections, powder hemostatics	First line for upper gastrointestinal tract
Radiology	CTA → angioembolization	If endoscopy/lower gastrointestinal tract failure
Surgery	Rarely, when other methods are ineffective	Rescue tactics
Medicines	PPIs, vasoactive for varicose veins	Reducing relapses

Prevention

Primary prevention – control of risk factors: rational gastroprotection in patients with non-steroidal anti-inflammatory drugs and anticoagulants, eradication of Helicobacter pylori in peptic ulcer disease, correction of anemia in pregnant women (oral iron 30-60 mg/day in the absence of anemia and therapeutic doses in anemia), vaccination and nutritional support. [51]

Secondary prevention—a patient blood management program: microtubes, reduced phlebotomy frequency, revision of automated laboratory test routines, and staff and patient training. This will reduce the risk of hospital-acquired anemia in fragile patients. [52]

For patients who have experienced upper gastrointestinal bleeding, the following are important: maintenance therapy with proton pump inhibitors, control of anticoagulants/antiplatelet agents (restart at the time recommended by the gastroenterologist), iron correction until ferritin is normalized. [53]

In obstetrics, prevention of postpartum hemorrhage involves high-quality antenatal care, team preparedness to use uterotonics and tranexamic acid, availability of balloon tamponade and angioembolization, and timely correction of iron deficiency before delivery. [54]

Forecast

The prognosis is determined by the source and rate of blood loss, age, comorbidities, and the speed of achieving hemostasis. In-hospital mortality for upper gastrointestinal bleeding ranges from 2-10%, increasing with age and the number of comorbidities. [55]

In trauma, timely initiation of massive transfusion protocols, damage-control procedures, and the use of holistic strategies (including whole blood, tranexamic acid, and VET navigation) significantly reduce the risk of death. However, hemorrhage remains a leading cause of preventable death. [56]

After stabilization, iron replacement (often intravenous) and targeted relapse prevention (PPI, Helicobacter pylori eradication, antithrombotic therapy monitoring, endoscopic and radiological surveillance if needed) are crucial for quality of life. Current data support the priority of intravenous iron for rapid hemoglobin restoration after gastrointestinal bleeding. [57]

In obstetrics, global mortality from postpartum hemorrhage is declining, but the burden remains high, particularly in resource-limited settings; implementation of protocols and access to embolization/blood are key to improving prognosis. [58]

FAQ

1) Why can hemoglobin be "normal" when a person is clearly bleeding?
Because the decrease in hemoglobin concentration is delayed due to hemodilution and infusions. Evaluate the clinical picture, lactate, and dynamics; repeat tests. Reticulocytosis usually appears after 3-4 days. [59]

2) When to perform endoscopy for upper gastrointestinal bleeding?
After stabilization - within 24 hours. "Ultra-urgent" endoscopy ≤12 hours for non-variceal bleeding has not shown benefit; for variceal bleeding, it is performed as soon as possible after stabilization. [60]

3) What is the threshold for red blood cell transfusion?
In stable adults, the benchmark is 70 g/L, but the decision is individualized based on clinical presentation and comorbidities. A restrictive strategy is safe and reduces unnecessary transfusions. [61]

4) What if endoscopy fails to stop the bleeding?
The next step is transcatheter arterial embolization (where available), which has demonstrated high technical and clinical efficacy; in fragile patients, it is preferable to surgery. [62]

5) Should everyone be given iron after bleeding?
Almost everyone with iron deficiency after blood loss; in moderate/severe anemia, intolerance to oral iron, or the need for rapid recovery, intravenous iron is more effective than oral iron. [63]

Appendix: Guidelines in Tables

Table 7. Components of the massive transfusion protocol (summary)

Component	Principle
Ratio of components	Red blood cells: plasma: platelets in balanced proportions
Early antifibrinolytic therapy	Tranexamic acid as soon as possible (within a “window” of up to 3 hours for trauma)
Ionized calcium	Maintain due to citrate load
Thermal management	Avoid hypothermia
Viscoelastic control	TEG/ROTEM for targeted correction

Table 8. Imaging for suspected gastrointestinal bleeding

Scenario	Preferred method	Alternative/addition
Upper GI tract, stable	EGDS ≤24 hours	CTA in case of doubt/heavy bleeding
Lower gastrointestinal tract, active bleeding	CTA → angiography/embolization	Radioisotope scanning in intermittent
Endoscopy failure	Angioembolization	Surgery