Ileal puncture: how bone marrow is collected, what the test reveals, and what the risks are

In clinical hematology, the term "iliac puncture" typically refers to the collection of bone marrow from the ilium, most commonly from the posterior iliac crest. In practice, this may include bone marrow aspiration, which is the extraction of the liquid portion, as well as trephine biopsy, which is the extraction of a cylinder of bone marrow tissue. This approach is considered the primary approach for adult patients. [1] [2] [3]

Aspiration and trephine biopsy serve different purposes. Aspiration better reveals individual cells, their shape, maturity, and quantitative ratio, while trephine biopsy allows for an assessment of the overall bone marrow architecture, its cellularity, cell distribution, infiltration, fibrosis, and other structural changes that cannot be reliably assessed from a liquid sample alone. [4] [5]

The posterior iliac crest is considered the preferred site for the procedure because it is relatively easily accessible, relatively safe, and allows for the collection of both aspirate and trephine biopsy specimens during a single procedure. The International Council for Standardization in Hematology explicitly lists the posterior iliac crest as the preferred anatomical approach for aspiration and trephine biopsy, while the anterior crest is used primarily when positioning the patient is difficult. [6] [7]

The modern approach assumes that aspirate and trephine biopsy do not compete with each other, but rather complement each other. International standards and current reviews emphasize that together they provide the most complete picture of bone marrow status, especially when it comes to complex oncohematological or myelodysplastic diagnostics. [8] [9]

It's also important to note that iliac puncture is not the same as the "old" sternal puncture. Sternal aspiration is used much less frequently today, only in certain circumstances and only by experienced specialists, as it is unsuitable for trephine biopsy and is associated with special risks. Therefore, in real-world practice today, when discussing bone marrow collection in adults, the iliac approach is most often considered. [10] [11]

Aspect	Ileal aspiration	Ileal trephine biopsy
What do they get?	The liquid part of bone marrow	Bone marrow tissue cylinder
The main strength of the method	Detailed cell assessment	Evaluation of architecture and cellularity
What is especially important	Blast count, morphology, additional laboratory tests	Fibrosis, infiltration, focal lesions, spatial distribution of cells
Can we do it together?	Yes, that's what they do most often.	Yes, usually within the same study
The main place of the fence	Posterior iliac crest	Posterior iliac crest

Sources for the table. [12] [13] [14]

When is this research really needed?

Ileal puncture is not performed "for prevention," but rather when routine blood tests are no longer sufficient. Mayo Clinic and MedlinePlus indicate that bone marrow examination is primarily needed for abnormal blood tests, when it is necessary to understand why there are too few or too many cells, or why they look atypical. [15] [16]

Typical indications include unexplained anemia, leukopenia, leukocytosis, thrombocytopenia, thrombocytosis, pancytopenia, polycythemia, suspected leukemia, lymphoma, multiple myeloma, myelodysplastic syndrome, myelofibrosis, and other blood and bone marrow disorders. Additionally, bone marrow examination is used for staging of certain tumors if there is a possibility that the disease has spread to the bone marrow.[17][18]

There are also less obvious clinical situations. Bone marrow is examined in cases of fever of unknown origin, if an infection or hidden hematological pathology is suspected, if cumulative diseases are suspected, during treatment monitoring, and also after chemotherapy or transplantation, when it is necessary to understand how hematopoiesis is restored. [19] [20]

International standards emphasize that in most cases, it is optimal to obtain both an aspirate and a trephine biopsy. This is especially important when it is necessary not only to confirm the presence of a pathology, but also to understand its type, prevalence, and structure. In some simpler clinical scenarios, an aspirate may be sufficient, but a combined biopsy is considered the most informative. [21] [22]

Before prescribing a procedure, the physician evaluates not only the indications but also the patient's safety. Medications and supplements that may increase the risk of bleeding, the presence of anxiety or a pronounced fear of pain, the need for sedation, and the patient's overall condition are discussed. Modern sources emphasize that preparation should be individualized, not formulaic. [23] [24]

When research is especially useful	What does it help to find out?
Unexplained changes in the complete blood count	Is there a bone marrow disease?
Suspected leukemia, lymphoma, multiple myeloma	Confirmation, classification, prevalence assessment
Treatment control	Does the therapy work and is hematopoiesis restored?
Suspected bone marrow metastases	Is there bone marrow damage?
Fever of unknown origin	Is there any infection or hidden hematological pathology?

Sources for the table. [25] [26] [27]

How to prepare for an iliac puncture and how it is performed

Most patients don't require any special, complex preparation. The Mayo Clinic notes that bone marrow examinations are often performed on an outpatient basis, without extensive preparation. Exceptions typically relate not to the bone marrow itself, but to planned sedation, during which the doctor may ask the patient to temporarily fast or refrain from eating or drinking. [28]

Before the procedure, the patient is asked to disclose all medications and supplements, especially if they may affect blood clotting. It is also important to discuss prior bleeding episodes, allergies, anxiety, tolerance of anesthesia, and whether a companion will be needed for the return journey home after sedation. [29] [30]

The harvesting procedure is most often performed in the lateral or prone position, so that the posterior iliac crest is accessible. The area is treated with an antiseptic and numbed with a local anesthetic, after which the doctor makes a small skin incision and inserts a needle into the bone. Local anesthesia is considered the primary pain relief option, with light sedation used as indicated or at the patient's request. [31] [32] [33]

During the aspiration, the patient may feel a brief but sharp pain or burning sensation as the liquid portion of the bone marrow is drawn into the syringe. Then, if a core biopsy is being performed, a larger needle is used to obtain a cylinder of tissue. The Mayo Clinic specifically emphasizes that the aspiration and biopsy typically take approximately 10-20 minutes, although preparation and observation may take longer. [34] [35]

After the procedure, pressure is applied to the puncture site to stop bleeding, a bandage is applied, and aftercare instructions are given. Typically, it is recommended to keep the bandage dry for 24 hours, avoid strenuous activity for 1-2 days, and monitor pain, bleeding, redness, swelling, and fever. If intravenous sedation was used, a more gentle regimen is needed on this day, and the journey home should not be a solitary one. [36] [37]

Stage	What's happening
Before the procedure	They clarify medications, the risk of bleeding, and the need for sedation
Patient position	Usually on the side or stomach
Anesthesia	Local anesthesia, sometimes additional light sedation
The main stage	First aspiration, then often trephine biopsy
After the procedure	Apply pressure to the puncture site, apply a bandage, and observe briefly.

Sources for the table. [38] [39] [40]

What can be seen in the material and why one sample is often not enough

After the iliac puncture, the material is sent to the laboratory, where it is evaluated by a pathologist or hematopathologist. The goal of the study is not only to find "bad cells" but also to understand whether the bone marrow is producing enough healthy cells, whether there is tumor infiltration, inflammation, fibrosis, hematopoietic depletion, or other pathological changes. [41] [42]

Aspirates are particularly valuable for cytological evaluation. They are used to examine cell morphology, perform blast counts, and, if necessary, perform flow cytometry, cytogenetic studies, fluorescent in situ hybridization, and molecular tests. Contemporary reviews emphasize that the combination of morphology and molecular methods today determines the accuracy of many oncohematological diagnoses. [43] [44]

A trephine biopsy provides other, equally important information. It reveals the cellularity of the bone marrow, the integrity of its architecture, the distribution of cell populations, the focality of the lesion, the severity of reticulin or collagen fibrosis, necrosis, granulomas, the degree of tumor infiltration, and a number of changes that simply cannot be reliably assessed from a liquid aspirate. This is why a trephine biopsy is particularly valuable in myelofibrosis, aplasia, focal infiltrates, and some lymphomas. [45] [46]

A particularly important situation is the so-called "dry puncture," when aspirate cannot be obtained or is extremely poor. Modern sources emphasize that this is not always a technical error. "Dry puncture" can be a sign of severe fibrosis, dense tumor infiltration, or other serious bone marrow pathology, and it is in such cases that trephine biopsy becomes especially important. [47] [48] [49]

The result is rarely summarized in a single line. Often, the final conclusion is based on data from peripheral blood, aspirate, trephine biopsy, flow cytometry, cytogenetics, molecular studies, and sometimes immunohistochemistry. It is this integrated approach that corresponds to the modern understanding of blood and bone marrow diseases in the era of the 2022 World Health Organization classifications. [50] [51]

Research component	What does he give to the doctor?
Aspirate	Cell morphology, blast count, material for additional laboratory tests
Trephine biopsy	Architecture, cellularity, fibrosis, focal infiltrates
Flow cytometry	Immune cell profile
Cytogenetics and molecular methods	Genetic and prognostic features of the disease
Joint interpretation	A more accurate and clinically meaningful diagnosis

Sources for the table. [52] [53] [54]

Risks, limitations, and what has changed in modern practice

Ileal puncture is generally considered a safe procedure, and serious complications are rare. The Mayo Clinic lists the main risks as bleeding, skin infection at the puncture site, and prolonged discomfort at the collection site. With the iliac approach, these risks are significantly lower than the rare but more dangerous complications described for sternal aspiration. [55] [56]

In practice, the most common patient problem is pain during aspiration and soreness in the following days. The Mayo Clinic and Merck Manual indicate that a brief pain pulse during aspiration is typical, and moderate tenderness at the puncture site may persist for 1 week or longer. Therefore, high-quality local anesthesia and an honest explanation of the sensations before the procedure are as important as the technique itself. [57] [58] [59]

The risk of bleeding is assessed on an individual basis. A recent review of anticoagulants in bone marrow biopsy describes the procedure as an intervention with a low to moderate risk of bleeding and emphasizes that routine discontinuation of anticoagulants is not always recommended, and the decision should depend on the specific clinical situation and the severity of hemostatic disorders. [60]

Another limitation is not related to safety, but to the quality of the sample. An aspirate that is too hemodiluted, a trephine biopsy that is too short, or a "dry puncture" can significantly reduce the diagnostic value of the test. This is why modern laboratory services increasingly focus on sample collection standards, sample quality control, and close communication between the clinician and hematopathologist. [61] [62]

The major change in recent years is that bone marrow is no longer assessed solely on a glass surface. Modern diagnostics rely on the integration of morphology, immunohistochemistry, flow cytometry, cytogenetics, and molecular methods, and the International Council for Standardization in Hematology continues to update individual components of this assessment, such as approaches to immunohistochemical testing of the CD34 marker in bone marrow. This makes iliac puncture not just a collection procedure, but an entry point into a multilayered modern diagnostic approach. [63] [64] [65]

Risk or limitation	What does this look like in practice?
Pain	Brief sharp pain during aspiration and soreness after the procedure
Bleeding	Usually minor, but requires individual assessment in case of hemostasis disorders
Infection	Rare, usually limited to the skin at the puncture site
Uninformative material	Hemodilution, short biopsy or dry puncture are possible.
Underestimating the complexity of the case	It is a mistake to rely only on morphology without additional methods

Sources for the table. [66] [67] [68] [69]

FAQ

Are ileal puncture and bone marrow biopsy the same thing?
Not quite. In clinical speech, the term "ileal puncture" is often used loosely, but technically, aspiration and trephine biopsy are two different methods of obtaining material from the same anatomical area. In modern practice, they are often performed together. [70] [71]

Why is the material typically taken from the posterior iliac crest?
Because this approach is considered the primary and most convenient for adults: it is relatively safe, allows for the collection of both types of material, and is well standardized by international recommendations. [72] [73]

Is it very painful?
A brief pain during aspiration is indeed typical, even with good local anesthesia. However, it is usually short-lived, and the severity of subsequent pain often subsides within a few days. If you are highly anxious or have a low pain threshold, you can discuss additional sedation with your doctor. [74] [75]

When might a result be uninformative?
Problems arise with hemodilution, too poor aspirate, a short biopsy, or a "dry puncture." This does not always indicate poor technique, as some bone marrow diseases themselves make it difficult to obtain a normal aspirate. [76] [77] [78]

Should blood thinners be discontinued?
There is no universal rule. A recent review suggests a low to moderate risk of bleeding with this procedure and that routine discontinuation of anticoagulants is not always recommended. The physician makes an individual decision, taking into account the diagnosis, risk of thrombosis, and coagulation parameters. [79]

When should you urgently contact your doctor after the procedure?
If bleeding soaks through the dressing or doesn't stop with pressure, if pain increases, if fever develops, or if redness, swelling, or discharge from the puncture site increases, the Mayo Clinic considers these signs to be reasons for urgently contacting your medical team. [80]

Key points from experts

Barbara Bain, Professor of Diagnostic Haematology, Honorary Consultant Haematologist, and Professor Emeritus at Imperial College London, has published a paper on the subject. The practical conclusion drawn from her work and international standards is that aspirate and trephine biopsy cannot be considered interchangeable. Complex diagnostics require comprehensive bone marrow analysis, not an attempt to "save" on one component. [81] [82]

Katherine R. Calvo, MD, PhD, is Chief of the Hematology Service and a Senior Scientist and Hematopathologist at the National Institutes of Health in the United States. The practical significance of her professional field is that modern bone marrow examination has long since moved beyond simple microscopy. Morphology is still fundamental, but a complete diagnosis increasingly requires a combination of morphology with immunohistochemistry, flow cytometry, and molecular methods. [83] [84] [85]

Tracy I. George, MD, Medical Director of Hematopathology, Professor of Clinical Pathology at the University of Utah School of Medicine, and Past President of the International Society of Laboratory Hematology. The key practical point here is this: the quality of a bone marrow examination is determined not only by how well the diagnosis is made at the end, but also by how well the sample is collected at the beginning. Good laboratory hematology starts with good material. [86] [87]

Conclusion

Ileal puncture is more than just a "bone prick," but a key diagnostic step that allows one to see what no standard blood test can reveal. Most often, it involves aspiration and trephine biopsy from the posterior iliac crest, as this approach offers the best balance of information yield and safety. [88] [89]

In practice, the value of the procedure is determined by three factors: correct indications, high-quality sample collection, and competent, modern interpretation. This is why today, iliac puncture is no longer an isolated procedure, but the beginning of a comprehensive, multi-level bone marrow examination. [90] [91]