Late postpartum hemorrhage refers to significant uterine bleeding occurring after 24 hours following childbirth and during the puerperium. It most commonly manifests 1–2 weeks postpartum, but in some cases, it can occur as late as over two months after delivery. Vaginal bleeding may present as small to moderate in volume, persisting continuously or intermittently, or as sudden heavy bleeding accompanied by the expulsion of blood clots. Associated symptoms among affected women include chills, low-grade fever, anemia, or hemorrhagic shock due to excessive blood loss.
Etiology and Clinical Manifestations
Retained Placenta or Membranes
Retained placental tissue is one of the most common causes of late postpartum hemorrhage after vaginal delivery, typically presenting around 10 days postpartum. Retained placental tissue within the uterine cavity undergoes degeneration, necrosis, and organization. When necrotic tissue detaches, the exposed basal blood vessels can cause significant bleeding. Clinical manifestations include prolonged persistence of lochia rubra, recurrent bleeding episodes, or sudden heavy bleeding. Examination may reveal subinvolution of the uterus with a relaxed cervix, and in some cases, retained tissue may be visible.
Retained Decidua
Normally, the decidua detaches within the first week postpartum and is expelled as part of the lochia. Partial detachment or prolonged retention of decidua can impair uterine involution, lead to secondary endometritis, and result in late postpartum hemorrhage. The clinical presentation closely resembles that of retained placental tissue, with pathological examination of uterine curettage material revealing necrotic decidua interspersed with fibrin, hyaline degenerative decidual cells, and red blood cells, but chorionic villi are absent.
Incomplete Involution of the Placental Attachment Site
Following delivery of the placenta, the attachment site undergoes rapid reduction in size, accompanied by the formation of thrombi in the blood vessels. These thrombi later organize, undergo hyaline degeneration, and are replaced by newly growing endometrium. Complete endometrial repair typically takes 6–8 weeks. In cases where placental attachment site involution is incomplete, thrombi at the site may dislodge, and reopened vascular sinuses can lead to uterine bleeding. This condition often arises around 2 weeks postpartum and presents with sudden profuse vaginal bleeding. Examination reveals an enlarged and soft uterus, a relaxed cervix, and blood clots within the vagina and cervical canal.
Infection
Uterine infections, particularly endometritis, are frequently implicated. Infection can impair placental site involution and compromise uterine contraction, leading to incomplete closure of vascular sinuses and subsequent uterine bleeding.
Poor Healing of Uterine Incisions After Cesarean Section
Poor healing of a cesarean section incision may result in bleeding due to several factors:
- Impaired blood supply to the transverse incision in the lower uterine segment: Branches from the uterine arteries may be disrupted at the distal ends of the incision, leading to localized ischemia. Insufficient hemostasis during surgery can result in local hematoma formation or tissue necrosis from infection, preventing proper healing. Multiple cesarean deliveries thin the incision site, reducing blood supply and creating scar tissue that further impairs wound healing. In cases where the fetal head is deeply engaged at the time of delivery, extension of the incision downward may cause tearing that complicates healing due to poor wound alignment.
- Improper choice of transverse incision site:
- When the incision is too low, it mainly involves cervical connective tissue, which has poor blood supply and healing capacity, and is located closer to the vagina, increasing the risk of infection.
- When the incision is too high, discrepancies in the thickness of the uterine body muscle at the incision's upper edge and the thinner lower uterine segment muscle at the lower edge make it difficult to align tissues during suturing, resulting in suboptimal healing.
- Incorrect suturing technique: Inadequate tissue alignment, careless surgical manipulation, failure to securely ligate bleeding vessels, and failure to suture vascular retractions at the angles of the incision may result in hematomas. Overly dense or excessive suturing can lead to poor blood supply at the incision site, further contributing to poor wound healing.
- Incisional infection: The proximity of the lower uterine segment transverse incision to the vagina increases the risk of infection. Additional risk factors include prolonged rupture of membranes, extended labor, repeated vaginal examinations, placenta previa, significant intraoperative bleeding, or anemia.
These factors collectively impair incision healing, leading to reopening of vascular sinuses and massive vaginal bleeding after the stitches dissolve, potentially resulting in shock.
Other Causes
Other notable causes of late postpartum hemorrhage include uterine arteriovenous malformations, uterine artery pseudoaneurysms, postpartum gestational trophoblastic tumors, submucosal uterine fibroids, and cervical cancer.
Diagnosis
Medical History
For vaginal delivery, the assessment includes progression of labor and changes in lochia, as well as any history of recurrent or sudden vaginal bleeding. For cesarean delivery, the surgical indication, procedure type, and postoperative recovery are considered.
Symptoms and Signs
Vaginal Bleeding
Vaginal bleeding caused by retained placenta or membranes and retained decidua typically occurs within 10 days postpartum. Incomplete involution of the placental attachment site often presents around 2 weeks postpartum, with episodes of recurrent bleeding or sudden heavy bleeding. Vaginal bleeding caused by cesarean section incision dehiscence or poor healing usually occurs 2–3 weeks after surgery and may manifest as sudden massive uterine bleeding, potentially resulting in hemorrhagic shock.
Abdominal Pain and Fever
Infection is often present, accompanied by an increase in lochia with a foul odor.
Systemic Symptoms
Secondary anemia and, in severe cases, life-threatening hemorrhagic shock due to blood loss.
Physical Examination
Signs of uterine subinvolution include an enlarged and softened uterus, a relaxed cervix, and possibly remnants of tissue or clots in the uterine cavity. Marked uterine tenderness may indicate infection.
Supplementary Investigations
These include:
- Blood Routine and Coagulation Tests: Assessment of anemia, coagulation status, and infection.
- Ultrasound Examination: Evaluation of uterine size, the presence of retained intrauterine material, the status of cesarean incisions, and identification of surrounding hematomas.
- Pathogen Culture and Sensitivity Testing: Culture of uterine cavity secretions and blood culture during fever episodes to determine effective broad-spectrum antibiotics.
- Serum hCG Levels: Helpful in excluding retained placenta and gestational trophoblastic disease.
- Pathological Examination: Analysis of uterine curettage material or hysterectomy specimens for definitive diagnosis.
- CT and MRI: Enables better evaluation of the extent of lesions and their relationship with the myometrium.
Management
Treatment is directed at the underlying cause.
For mild to moderate vaginal bleeding, management includes broad-spectrum antibiotics, uterotonics, traditional Chinese medicine preparations, and supportive therapies. In cases of significant vaginal bleeding with hemodynamic instability, emergency intervention is required.
If retained placenta, membranes, or decidua is suspected, uterine evacuation (curettage) may be performed under conditions of adequate intravenous fluids, blood availability, and surgical preparation. Careful surgical technique is important to avoid uterine perforation. Curettage material is sent for pathological examination for diagnostic confirmation. Postoperatively, administration of antibiotics and uterotonics should continue.
If cesarean incision dehiscence is suspected, even cases with minimal vaginal bleeding are recommended for hospitalization. Treatment includes administration of broad-spectrum antibiotics and supportive care with close monitoring of clinical status. For significant vaginal bleeding, exploratory laparotomy or laparoscopy may be performed.
For cases with a small area of tissue necrosis and minimal inflammatory response around the incision, debridement, suturing, and ligation of the uterine or iliac arteries can help control bleeding.
In instances of pseudoaneurysm formation at the incision site, embolization of the uterine or iliac arteries is the preferred treatment.
Extensive tissue necrosis may require subtotal or total hysterectomy, depending on the severity.
Vaginal bleeding caused by tumors is treated according to the tumor's nature and location.
Prevention
Risk factors for bleeding tendencies should be identified, with appropriate investigations undertaken.
Careful examination of the placenta and membranes postpartum is essential, with removal of residual fragments if incomplete expulsion is observed. If retained placenta cannot be excluded, uterine exploration should be conducted.
During cesarean delivery, proper incision site selection is crucial to avoid tearing at the corners of the lower uterine segment transverse incision and to ensure appropriate suturing techniques are applied.
Adherence to strict aseptic technique during surgery and postoperative antibiotic prophylaxis can help reduce infection risks.