Spontaneous retroperitoneal hemorrhage due to rupture of a renal angiolipoma in a 37-week pregnancy: a case of Wünderlich syndrome

Abstract

Introduction

Wünderlich syndrome is defined as spontaneous, non-traumatic retroperitoneal bleeding, often associated with the rupture of a renal angiomyolipoma. Though rare, this condition is life-threatening if not treated promptly. The syndrome is particularly uncommon during pregnancy, posing significant challenges in diagnosis and management due to overlapping symptoms with other obstetric emergencies.

Case Presentation

We report the case of a 25-year-old woman at 37 weeks of gestation who presented to the emergency department with hypovolemic shock, left flank pain, and fetal bradycardia. A large retroperitoneal hematoma was discovered during an emergency caesarean section, later identified as secondary to a ruptured renal angiomyolipoma. Despite the critical presentation, a total nephrectomy was performed successfully, and both mother and child had favorable outcomes.

Conclusion

This case highlights the importance of considering Wünderlich syndrome in differential diagnoses of acute abdominal pain during pregnancy, especially in the presence of shock and renal masses. Prompt interdisciplinary management is crucial for positive maternal and fetal outcomes.

Introduction

Wünderlich syndrome refers to spontaneous retroperitoneal hemorrhage, primarily involving the subcapsular and perirenal space, with the rupture of renal angiomyolipoma as the most common cause. ¹ It can result from other conditions such as renal neoplasms, vasculitis, and aneurysms. ² The incidence of renal angiomyolipoma in the general population is estimated to be between 0.1% and 0.3%, with a higher prevalence in women, particularly between the fourth and sixth decades of life. During pregnancy, although exact data is lacking, it has been reported that hormonal changes, such as increased levels of estrogen and progesterone, can accelerate the growth of angiomyolipoma in previously diagnosed women. ³ The most frequent symptoms include acute abdominal pain, a palpable mass, and signs of hypovolemic shock, collectively known as Lenk's triad. ⁴ Diagnosing Wünderlich syndrome during pregnancy can be particularly challenging due to overlapping symptoms with other obstetric complications. ⁵ Renal angiomyolipomas typically present as fat-rich masses on CT, with low attenuation and moderate contrast enhancement. On MRI, they show signal loss on fat-suppressed sequences, hyperintensity on T1, and variable T2 signals. Fat-poor renal angiomyolipomas are more challenging to distinguish from renal cell carcinoma. Surgery is indicated for tumors >4 cm, symptomatic cases (pain, hemorrhage), rapid growth, diagnostic uncertainty, or failure of conservative measures. Interventions include partial or radical nephrectomy and selective embolization, depending on tumor size, symptoms, and renal function. ³ This report presents a case of Wünderlich syndrome in a full-term pregnant woman, managed successfully with emergency intervention.

Patient information

A 25 year-old woman in her second pregnancy, with an otherwise uneventful pregnancy at 37 + 0 weeks of gestation, presented to the emergency department at San Ignacio University Hospital, Bogotá, Colombia. She arrived with her husband, who reported a sudden onset of intense left flank pain, followed by an episode of near fainting. The patient had no history of trauma nor urinary complaints, no significant medical or surgical history, and her prenatal course had been uneventful up to this point.

Clinical findings

On examination, the patient was somnolent, pale, and diaphoretic, with vital signs indicating hypovolemic shock (blood pressure: 91/52 mmHg, heart rate: 116 beats/min, respiratory rate: 18 breaths/min, oxygen saturation: 87% on room air). Her abdomen was distended with a gravid uterus, and she had marked tenderness over the left flank. Obstetric examination revealed no cervical changes or signs of vaginal bleeding, but fetal monitoring indicated bradycardia (46 beats/min).

Diagnostic assessment

Given the clinical findings, a presumptive diagnosis of placental abruption was made, and an emergency caesarean section was performed. During surgery, a live male infant was delivered with APGAR scores of 0/10 at 1 minute and 10/10 at 5 minutes. Examination of the maternal retroperitoneal space revealed a large hematoma (2500 cc) extending from zone I to zone II on the left side. At that moment, since the source of the bleeding could not be located and due to the hemorrhagic shock with hemodynamic instability, it was decided to perform damage control with packing, and a massive transfusion protocol was initiated (initial Hb: 7.7 g/dL, post-transfusion Hb: 9.1 g/dL). Once stabilized, the patient underwent an abdominal aorta CT angiogram, which revealed left retroperitoneal hemorrhage secondary to bleeding from a left renal angiomyolipoma (Wünderlich syndrome), measuring 100 × 80 × 70 mm (Figures 1 and 2).

Figure 1.

Axial view of abdominal aorta angiotomography with evidence of left renal angiomyolipoma, measuring 100 × 80 × 70 mm (red arrow).

Figure 2.

Coronal view of abdominal aorta angiotomography with evidence of left renal angiomyolipoma, measuring 100 × 80 × 70 mm (red arrow).

Therapeutic intervention

Following selective embolization of the renal vessels on the day of delivery, 2 days later a total left nephrectomy was performed in a planned second surgery. This was because the mass measured more than 4 cm and continued with active bleeding, despite initial management.

The resected mass was highly vascularized and occupied the upper two-thirds of the kidney (Figure 2). The final histology of the specimen was a classic angiomyolipoma, with free margins, a size of 8.4 cm, and immunohistochemical markers positive for AML, MELAN A, and HMB45 (Figure 3).

Figure 3.

Surgical specimen: renal mass with a lipomatous appearance, highly vascularized, occupying the upper two-thirds of the left kidney.

Outcome and follow-up

Postoperatively, the patient recovered well, with stable vital signs and no further complications. She was discharged 4 days after surgery and seen in follow-up 10 days later, demonstrating good postoperative recovery. The infant was also healthy at follow-up.

Discussion

Wünderlich syndrome, first detailed by Carl Reinhold August Wünderlich in 1856, ⁴ is a rare but critical condition characterized by spontaneous retroperitoneal hemorrhage, often caused by ruptured angiomyolipomas. ⁶ The majority of cases occur in women, with a female-to-male ratio of 4:1. ⁷ During pregnancy, its presentation is exceptionally rare, making diagnosis difficult due to symptom overlap with other obstetric emergencies, such as placental abruption. Early recognition and prompt interdisciplinary intervention are critical for maternal and fetal survival.

Imaging studies such as CT scans and MRI are crucial for diagnosis, ⁸ but in emergent settings, immediate surgical intervention may be necessary before confirmatory imaging. ⁹ In cases of significant hemorrhage, nephrectomy is often the treatment of choice. ¹⁰

This case underscores the importance of considering Wünderlich syndrome in pregnant patients with acute abdominal pain and shock, particularly in the context of renal masses. Proper management by a multidisciplinary team, including obstetricians, urologists, and general surgeons, is essential for optimizing outcomes.