Missed Abdominal Wall Hernias

INTRODUCTION

Missed hernias are defined as true hernias that are not recognized at the time of operative exploration. They represent a vexing problem for surgeons, as the diagnosis of abdominal wall hernias continues to rely primarily on physical examination.¹ Therefore, the general surgeon must be prepared to manage unexpected intraoperative findings when a patient’s presentation is consistent with a hernia, but no hernia is seen intraoperatively. This can occur when a femoral hernia is missed during an open exploration for an inguinal hernia, but is also seen with open repair of Spigelian hernias and transabdominal preperitoneal (TAPP) repair of inguinal hernias. This manuscript will review these 3 categories of missed hernias and discuss ways to avoid this operative error. The discussion of each type of hernia will begin with a case presentation* followed by a full discussion. (*These case reports are constructed for educational purposes and the details of the clinical care do not represent the story or the imaging for any individual patient).

OPEN REPAIR OF FEMORAL HERNIA

Case Report #1

An 85-year-old female presented to the clinic with right groin pain. The patient was healthy, other than mild dementia and a BMI of 32. The right groin had a reducible bulge, and the left was normal. The patient was offered an open repair under sedation. During the operation, after the round ligament was resected, the floor was felt to be very weak and a piece mesh was used to reconstruct the floor. The patient went home and did well until 2 weeks postoperatively, when she presented to the emergency room with a bowel obstruction. A CT scan (Fig. 1) was obtained, which showed an incarcerated femoral hernia.

FIGURE 1.

This CT scan demonstrates a right femoral hernia with a piece of small bowel incarcerated in the defect.

Discussion of Missed Femoral Hernias

The history of missed femoral hernia during open inguinal hernia repair has been well chronicled.² Femoral hernias often present late, due to the lack of symptoms or a confusing physical exam.³ During an open repair, the floor of an inguinal canal, especially in the elderly patient, may be very weak and give the suggestion of a direct hernia. Care must be taken to open the floor and look for a femoral hernia if an actual hernia sac is not seen when the cord or round ligament is mobilized off the floor. It is not routine to open the floor during hernia repair, so the key question is; when do you open the floor? History, physical exam, and ultrasound imaging are not always useful in differentiating direct hernia from femoral hernia preoperatively.⁴ The laparoscopic approach to inguinal hernias will minimize the chance of missing a femoral hernia, but some patients are better suited for open surgery. Therefore, during open repair of inguinal hernias, surgeons need to have a low threshold to open the floor of the inguinal canal to look for a femoral hernia if an indirect or direct hernia sac is not encountered.

OPEN REPAIR OF SPIGELIAN HERNIA

Case Report #2

A 60-year-old male presented with pain in the left lower quadrant. The patient had a history of a laparoscopic appendectomy, where significant bilateral pelvic inflammation/adhesive disease was noted. On exam, the surgeon could feel a bulge in the left lower quadrant near an old 5 mm trocar site, which was easy to reduce. The diagnosis was made of Spigelian hernia versus trocar site hernia, and an open operation was recommended. Under a general anesthetic, a left lower quadrant incision was made over the bulge that was marked preoperatively. When the rectus fascia and the fascia of the external oblique were observed, there was no hernia defect encountered. The surgeon closed without doing a repair. Three weeks later, the patient was admitted with a bowel obstruction. A CT scan (Fig. 2) showed a Spigelian hernia beneath the external oblique fascia and lateral to the rectus. The patient was reexplored through a left lower quadrant incision and the incarcerated Spigelian hernia was encountered when the fascia of the external oblique was opened. The incarcerated bowel was reduced, and the hernia defect was primarily closed.

FIGURE 2.

The arrow points to a left Spigelian hernia with an incarcerated loop of bowel.

Discussion of Missed Spigelian Hernia

This is a classic missed hernia story for open repair of Spigelian hernias. The correct approach is to open the external oblique fascia when exploring for a Spigelian hernia.⁵ Without opening the external oblique, the abdominal wall looks completely intact. The occult presentation of a Spigelian hernia was first described in 1909, but has become less common in the age of frequent CT scanning for abdominal wall hernias.⁶ Laparoscopic exploration for these hernias eliminates the possibility of this “miss” since the fascia defect is easily seen from the peritoneal surface as soon as the abdomen is insufflated.

Other small abdominal wall hernias can be missed during open or laparoscopic repairs. Small hernias of the upper abdominal wall may be hard to feel while the patient is anesthetized so preoperative marking becomes essential. Intraoperative ultrasound of the abdominal wall can also be helpful to find these defects, and laparoscopy can also be used along with palpation to search along the midline for small fat epigastric hernias obscured by the falciform ligament.

LAPAROSCOPIC TRANSABDOMINAL PREPERITONEAL REPAIR OF DIRECT HERNIA

Case Report #3

A 50-year-old male presented with a reducible bulge in the left groin. The physical exam was consistent with an inguinal hernia. During the TAPP laparoscopic exploration, no hernia was seen in the direct or indirect spaces. It was presumed that the bulge seen on preoperative physical exam was a lipoma of the cord. The peritoneum was taken down and a lipoma of the cord was resected laparoscopically, and mesh was placed. On postoperative day 4, the patient contacted the surgeon to report that the hernia had “recurred.” A CT scan (Fig. 3) showed that the bladder was protruding through the direct space medical to the mesh repair.

FIGURE 3.

This pelvic CT scan shows a bladder-filled left direct space hernia that protrudes just medial to the previously placed TAPP mesh repair. A surgical tack can be seen near the pubic tubercle marking the medial margin of the mesh.

Discussion of Missed Inguinal Hernias During TAPP

Missed direct hernias rarely occur during open or totally extraperitoneal hernia repair, but can occur in TAPP hernia repair. In the totally extraperitoneal approach, the balloon automatically dissects the peritoneum off of the pubis and the direct space, making a missed direct hernia less likely.⁷ In this case, the obvious technical error was not fully mobilizing the bladder off the pubis. When the anterior wall of the bladder fills a direct space hernia, the hernia may not be visible intraperitoneally. In these cases, the peritoneal side of the bladder may look normal and may not be prolapsing into the direct hernia defect. During a TAPP, if a hernia is not immediately apparent, the most common teaching is that the “bulge” appreciated on preoperative exam was due to a lipoma of the cord. That bias can lead the surgeon to not specifically look for a bladder-filled direct space hernia.

A missed indirect sac during open hernia repair has been described in the literature, as well as ways to avoid this complication.⁸ During a TAPP repair, an indirect hernia may be missed if the peritoneum is not taken down from the internal ring. During that dissection, the indirect space must be fully explored to rule out an occult hernia sac. A communicating hydrocele or patent processus vaginalis can present with a bulge in the groin on physical exam, but may be missed laparoscopically if the peritoneum is not taken down. Hydrocele of the canal of Nuck in women can also present as a hernia and can be managed laparoscopically by taking down the peritoneum and resecting the sac.⁹

CONCLUSIONS

Prior to the introduction of laparoscopic hernia repair, open exploration routinely allowed for finding and resecting patent processus vaginalis, bladder-filled direct hernias and femoral hernias if the surgeon was careful to open the floor when appropriate. In contrast, open hernia repair is not able to evaluate the contralateral side and only addresses unilateral repair. Laparoscopic hernia repair has introduced several advantages for patients, including evaluation of the contralateral side, less pain and speedier recovery compared to open repair. The challenge is that TAPP repair will occasionally miss a direct or indirect hernia if the peritoneum is not completely taken down. We therefore advocate that in all cases where a hernia is appreciated on exam, the peritoneum be taken down and a complete dissection performed in order to minimize the risk of a missed hernia regardless of whether or not a clear hernia can be seen at laparoscopy.

A missed femoral hernia can occur during open inguinal exploration. This complication can be avoided by having a high index of suspicion for a femoral hernia and opening the floor of the inguinal canal if routine exploration of the floor and cord has not revealed a direct or indirect hernia. Missed Spigelian hernias occur during open surgery and can be avoided if the surgeon understands that these hernias require that the external oblique be opened to visualize the fascial defect. The use of minimally invasive surgery for inguinal and Spigelian hernias, when done correctly, reduces the possibility of missed occult hernias as these defects can be readily identified and appropriately treated via intraperitoneal and preperitoneal approaches.