Banjo curettage is a common surgical technique used to remove placental tissue that remains in the uterus after delivery. The name comes from the instrument itself, a large, blunt, oval-looped curette whose shape loosely resembles a banjo. Clinicians pass it through the dilated cervix and sweep the uterine cavity to detach and extract fragments of placenta or membranes that did not deliver spontaneously. The procedure is straightforward in concept, but it carries real risks to the uterine lining, and newer approaches are changing how some hospitals handle the problem.
Why Placenta Gets Retained in the First Place
After a baby is delivered, the muscle layer behind the placenta normally contracts, shearing the placenta away from the uterine wall and pushing it out. When that contraction fails or is insufficient, the placenta stays put.1PubMed Central. The retained placenta Three overlapping mechanisms explain most cases. The first is inadequate uterine contractility, where the muscle simply does not squeeze hard enough. The second is abnormally invasive placentation, where placental tissue has grown too deeply into the uterine wall, as in the spectrum of conditions ranging from placenta accreta to placenta percreta. The third is premature cervical closure, where the cervix narrows before the placenta can pass through.2PubMed Central. Retained placenta after vaginal delivery: risk factors and management A population-based study found supporting epidemiologic evidence for all three mechanisms, along with a role for placental hypoperfusion, where poor blood flow to the placenta during pregnancy may predispose it to incomplete separation at delivery.3PubMed. Underlying mechanisms of retained placenta: Evidence from a population based cohort study
These distinctions matter clinically because the underlying cause affects how easily the tissue can be removed. A placenta that simply did not contract out is usually softer, less adherent, and responds more readily to manual extraction or curettage. One that has invaded the uterine wall may not come away cleanly no matter what instrument is used, and blind scraping in that situation raises the risk of heavy bleeding and perforation.
How Retained Tissue Is Diagnosed
Retained placenta is suspected when the placenta has not delivered within 30 to 60 minutes of the baby, or when a woman develops heavy bleeding, fever, or foul-smelling discharge in the days and weeks afterward. Ultrasound is the primary diagnostic tool, though interpreting postpartum scans is trickier than many people realize.
On standard gray-scale ultrasound, clinicians look for a thickened endometrial stripe or a distinct mass inside the uterine cavity. An endometrial thickness above about 10 mm raises suspicion, and a visible echogenic mass is a stronger indicator. A systematic review and meta-analysis found that an echogenic mass had the highest accuracy for predicting retained tissue, with sensitivity above 90% and specificity around 84%.4American Journal of Obstetrics & Gynecology. The accuracy of ultrasound scan in diagnosing retained products of conception: a systematic review and meta-analysis Color Doppler, which highlights blood flow, can add information. When increased vascularity appears inside a thickened lining or a mass, it raises sensitivity for retained tissue, but specificity drops considerably because a normal postpartum uterus can also show these patterns.5PubMed Central. The value of postpartum ultrasound for the diagnosis of retained products of conception: A systematic review In other words, ultrasound is better at ruling in retained tissue than ruling it out. A clearly visible mass is fairly reliable; a thickened lining alone is ambiguous. Gray-scale findings by themselves are considered insufficient for an accurate diagnosis, and adding Doppler improves the picture but does not make it definitive.6PubMed. Physiologic, histologic, and imaging features of retained products of conception
This diagnostic uncertainty matters for curettage decisions. If the scan is equivocal, a clinician faces a judgment call: proceed with surgery and risk scraping a uterus that may have already emptied itself, or wait and risk ongoing bleeding and infection from tissue that is actually there.
How the Procedure Is Performed
In its most traditional form, banjo curettage is a “blind” procedure, meaning the surgeon works by feel rather than direct visualization. After anesthesia (typically general or regional), the cervix is dilated if needed, and the banjo curette is inserted into the uterine cavity. The surgeon sweeps the inner surface of the uterus systematically, using the broad loop of the curette to scrape tissue off the uterine wall. The placental fragments are drawn out through the cervix, and the process is repeated until the cavity feels smooth and empty to the touch. The word “banjo” simply describes the instrument’s shape; the technique is essentially the same as any sharp or blunt curettage, just using a larger curette suited to the postpartum uterine cavity.
The procedure typically takes 15 to 30 minutes. What makes it challenging is that the postpartum uterus is large, soft, and highly vascular. The muscle wall is much thinner than in a non-pregnant state, and blood supply to the area is enormous. These factors together mean that the margin for error between effective scraping and going too deep is smaller than it might be during, say, a routine endometrial biopsy.
Risks of Blind Curettage
The most immediate danger during curettage is uterine perforation, where the instrument passes through the wall of the uterus. The soft, postpartum uterus is particularly susceptible. Perforations during postpartum curettage for adherent placenta have been documented in the literature, and severe cases can involve injury to surrounding organs and require emergency laparotomy.7PubMed Central. Obstetric Outcomes after Perforation of Uterine Cavity Hemorrhage is the other acute concern. The placental bed is richly supplied with blood vessels, and disturbing partially separated tissue can provoke significant bleeding.
A case series examining ultrasound-guided instrumental removal of retained placenta found that severe hemorrhage (1,000 mL or more during the procedure) occurred in about 7% of patients, and one patient required intensive care and uterine artery embolization afterward. Overall severe postoperative complications occurred in roughly the same proportion.8PubMed Central. The safety and effectiveness of ultrasound-guided instrumental removal of retained placenta after failed removal immediately after delivery Those numbers come from cases where ultrasound was guiding the procedure. With purely blind curettage, the complication rate may be higher, since the surgeon has no real-time visual feedback about curette position or wall thickness.
Intrauterine Adhesions and Future Fertility
Beyond the immediate surgical risks, the long-term concern with curettage for retained placenta is damage to the endometrial lining. When the curette scrapes away placental tissue, it inevitably strips some of the underlying basal layer of the endometrium as well. If enough lining is lost, scar bands can form inside the uterine cavity. This is known as Asherman’s syndrome, and it can cause menstrual changes, pain, and difficulty getting pregnant again.
A prospective study specifically looked at women undergoing secondary removal of placental remnants after delivery or repeat curettage for incomplete abortion. Hysteroscopy performed three months later found intrauterine adhesions in 40% of the women. Among those who developed menstrual disorders afterward, the risk of moderate-to-severe adhesions was about 12 times higher.9Human Reproduction. Prevalence of Asherman’s syndrome after secondary removal of placental remnants or a repeat curettage for incomplete abortion That 40% figure is sobering, though it is worth noting that many of those adhesions were mild, and the study specifically looked at secondary procedures (not first-pass curettage immediately after delivery). Still, it underscores that curettage of the postpartum uterus is not a benign event for the lining.
A comparative study of women who had curettage versus those who had hysteroscopic resection for retained tissue found meaningful differences in fertility outcomes. The rate of newly diagnosed infertility problems was about twice as high after curettage as after hysteroscopy, roughly one in four versus one in eight. These new problems were mechanical, involving tubal blockage and intrauterine adhesions. On average, time to conception after curettage was nearly 13 months, compared to about 7 months after hysteroscopy.10PubMed. A comparison of reproductive outcomes following hysteroscopic management versus dilatation and curettage of retained products of conception A more recent retrospective comparison found a similar trend: time to conception was shorter in the hysteroscopy group, though the difference in that smaller study did not reach statistical significance.11PubMed. A retrospective comparison of hysteroscopic resection and curettage in the treatment of retained products of conception: surgical and reproductive outcomes
For someone who plans future pregnancies, these data lean in favor of hysteroscopy when it is available and clinically appropriate. For emergency situations involving hemorrhage, waiting for hysteroscopic setup may not be realistic.
Ultrasound Guidance During Curettage
One of the simplest ways to reduce the risks of blind curettage is to add real-time ultrasound guidance. A clinician or sonographer holds an abdominal ultrasound probe during the procedure, allowing the surgeon to see the curette’s position inside the uterus on screen. This makes it far easier to identify where retained tissue is located, to confirm when the cavity has been adequately cleared, and to avoid pushing the instrument through the uterine wall.
A case series of ultrasound-guided instrumental removal for retained placenta reported a success rate of about 98%, with only one case requiring conversion to laparotomy. Median blood loss was modest at 50 mL, and while a small subset of patients experienced serious complications, no new-onset sepsis was observed.12PubMed Central. The safety and effectiveness of ultrasound-guided instrumental removal of retained placenta after failed removal immediately after delivery Ultrasound guidance does not eliminate all risks, but it fundamentally changes the procedure from one performed by feel alone to one with visual confirmation. In many institutions it is now considered standard practice, though access varies depending on staffing and resources.
Hysteroscopic Resection as an Alternative
Hysteroscopy offers a fundamentally different approach. Instead of scraping blindly or semi-blindly, the surgeon inserts a narrow camera and cutting instrument through the cervix and works under direct visualization. The retained tissue can be identified precisely and resected without disturbing the surrounding healthy lining. This selectivity is what appears to protect fertility.
The comparative data, though limited to retrospective and small studies, consistently point in the same direction. Hysteroscopic management is associated with fewer adhesions, faster return to conception, and lower rates of new mechanical infertility compared to curettage.13PubMed. A comparison of reproductive outcomes following hysteroscopic management versus dilatation and curettage of retained products of conception On logistic regression, hysteroscopic resection was linked to roughly half the odds of developing a new infertility problem relative to curettage.
The trade-offs are practical. Hysteroscopy requires specific equipment, a trained operator, and more operating time. The recent retrospective study found that operative time was significantly longer for hysteroscopy, and the procedure tended to be used later, at a median of about four weeks after delivery rather than one week.14PubMed. A retrospective comparison of hysteroscopic resection and curettage in the treatment of retained products of conception: surgical and reproductive outcomes That timing difference reflects real-world clinical practice: curettage is the go-to for acute situations, while hysteroscopy tends to be reserved for cases diagnosed later or after a first-line treatment has failed. In an acute hemorrhage scenario, the speed and simplicity of banjo curettage may be lifesaving. When the clinical situation allows a bit more time and the patient’s future fertility is a priority, hysteroscopy is worth discussing.
Medical Approaches That Have Been Tested
Researchers have investigated whether medication could avoid the need for surgery altogether. The logic is appealing: if the placenta is retained because the uterine muscle is not contracting properly, giving a drug that triggers contractions might expel the tissue without any instruments entering the uterus.
A meta-analysis of randomized trials on retained placenta management examined various agents injected through the umbilical vein to try to deliver the drug directly to the placental bed. Oxytocin, the most commonly used agent, turned out to be less effective than carbetocin and prostaglandins for avoiding the need for manual removal.15American Journal of Obstetrics & Gynecology. Management of retained placenta: a meta-analysis Nitroglycerin, a muscle relaxant, was tested in a large UK randomized trial under the theory that relaxing the uterus and cervix might allow the placenta to pass. It did not work: more than 90% of women in both the nitroglycerin and placebo groups still required manual removal of the placenta within 15 minutes.16PLOS Medicine. Nitroglycerin for treatment of retained placenta: A randomised, placebo-controlled, multicentre, double-blind trial in the UK Medical management, in short, has not yet proven reliable enough to replace surgical intervention for most cases. The evidence is thin, and no single drug has emerged as a dependable alternative to manual removal or curettage.
Antibiotic Prophylaxis
Infection is a real concern with any procedure that introduces instruments into the postpartum uterus. The retained tissue itself can serve as a nidus for bacteria, and the procedure disrupts the raw surface of the placental bed, creating a potential entry point for infection. Many clinicians give antibiotics before or during the procedure as a precaution, but the evidence behind this practice is surprisingly weak. A review of the literature on antibiotic prophylaxis for postpartum curettage concluded that there is insufficient evidence to argue either for or against routine prophylactic antibiotics at the time of the procedure.17Journal of Obstetrics and Gynaecology Canada. Antibiotic Prophylaxis in Obstetric Procedures In practice, many hospitals administer a single broad-spectrum dose before the procedure, reasoning that the potential benefit outweighs the minimal risk of one dose. But that is clinical judgment, not strong evidence-based medicine.
Anesthesia for the Procedure
How banjo curettage is managed from a pain standpoint varies widely. In emergency settings, particularly when the patient is already hemorrhaging, general anesthesia is common because it is fast and allows the surgeon to work without the patient experiencing a deeply unpleasant procedure. Regional anesthesia (spinal or epidural) is another option, especially if the patient already has an epidural in place from labor.
The evidence base for optimal anesthesia during manual removal or curettage of retained placenta is remarkably thin. A Cochrane systematic review on the topic identified only a single randomized trial of 30 women, which compared a paracervical block against intravenous sedation. That trial found no clear difference in outcomes, but with only 30 participants, it could not detect meaningful differences even if they existed. The review rated the certainty of evidence as very low and could not draw firm conclusions about which approach provides better pain relief or patient satisfaction.18Cochrane Database of Systematic Reviews. Anaesthesia/analgesia for manual removal of retained placenta Most clinical decisions about anesthesia for this procedure are driven by local practice patterns, what is already in place, and the urgency of the situation rather than by randomized evidence.
When Curettage Happens in Resource-Limited Settings
In hospitals with full surgical suites, hysteroscopy, and interventional radiology backup, the conversation about managing retained placenta involves a range of options. In many parts of the world, the banjo curette or its equivalent is all that is available. Manual removal, where the clinician’s gloved hand enters the uterus to peel the placenta off the wall, is the first-line approach in most settings. When that fails or when fragments remain, curettage with whatever instruments are on hand becomes the fallback.
Retained placenta remains a significant cause of postpartum hemorrhage globally, and hemorrhage is the leading cause of maternal death in low-resource settings. The simplicity of curettage is both its strength and its limitation. It requires no specialized equipment beyond the curette itself and basic surgical setup. But without ultrasound guidance, without hysteroscopy as an alternative, and sometimes without reliable anesthesia, the risks of perforation and adhesion formation are likely higher than what the published literature from well-equipped institutions reports. Efforts to improve training through simulation models are underway, reflecting the recognition that technique matters enormously in a procedure where the difference between effective clearance and catastrophic perforation comes down to the surgeon’s feel for tissue resistance.
For patients in settings where curettage is the only option, the practical takeaway is that postoperative monitoring matters. Changes in menstrual patterns after the procedure, particularly lighter or absent periods, warrant follow-up evaluation for intrauterine adhesions, since early detection and treatment of adhesions can preserve fertility.19Human Reproduction. Prevalence of Asherman’s syndrome after secondary removal of placental remnants or a repeat curettage for incomplete abortion