Iliohypogastric Nerve Entrapment with Robotic Trocar Site Closure

Recently, I performed a pyeloplasty in a grade school boy. After surgery, when we tried to get him out of the bed, he felt excruciating pain in the right lower quadrant trocar site. He described it as “the worst pain in my life”. We tried unsuccessfully ketorolac, acetaminophen, oxycodone, morphine, and warm compresses.

He only felt the pain in the right lower quadrant trocar site and not the other trocar sites. His vital signs and urine output were normal. He was keeping food and liquids down, with a soft and non-tender abdomen. The pain only happened when he tried to get out of bed.

Because this is not the typical postoperative course after a pyeloplasty, I suspected we caught a nerve with the fascial closure. We took him back to the operating room on POD# 2 and under mask anesthesia, we opened the trocar site skin, removed the 2-0 suture, and reclosed the fascia –this time only closing the external oblique fascia with small bites of a 3-0 suture. As soon as he woke up, he was able to get out of bed, walk, and he left the hospital a few hours later.

 

What happened?

Whiteside et al study on cadavers found that the ilioinguinal and iliohypogastric nerves emerge from the internal oblique muscle near the anterior superior iliac spine (ASIS). Both nerves transverse in between the internal and external oblique muscles terminating in the midline –iliohypogastric nerve- and the inguinal canal –ilioinguinal nerve. The ilioinguinal nerve emerged on average 3 cm medial and 3 cm inferior to the ASIS, whereas the iliohypogastric emerged 2 cm medial and 1 cm inferior to the ASIS. Based on this study, it is likely that my patient had his iliohypogastric nerve entrapped with the fascial suture.

Shin et al found a 5% incidence of neuropathic pain due to entrapment of the iliohypogastric-ilioinguinal nerve with fascial closure of laparoscopic incisions in the lower abdomen. The pain went away with suture removal with no cases of nerve entrapment among the patients who did not have closure of the fascia.

 

Should all ports be closed?

In adults, 8 mm trocar sites are not closed. It is recommended however to close all trocar sites greater than 3 mm in pediatrics.

Cost et al analyzed 218 laparoscopic procedures. Postoperative incisional hernias occurred in 7 (3%) at a median time of 1.2 months. Four of the seven hernias resolved with observation and the other 3 were repaired right away because of symptoms on postoperative day 1. Age was a risk factor with all hernia cases occurring in children younger than 4 years.

Paya et al also published on trocar site hernias after laparoscopic surgery. They reported on 3 postoperative trocar site hernias of omentum, all in lateral ports of 2,3 and 5 mm and in patients younger than 5 years.

 

Lessons learned

  • Midline fascial closures can be more “aggressive” as there are no nerves in that area and because some studies have found more hernias in the midline compared to lateral ports.
  • Lateral ports, especially in children older than 5 years, should be closed less aggressively — with small bites of just the external oblique muscle, using smaller suture –, as the closure can be associated with pain or nerve entrapment and the risk of hernia is fairly low.
  • For younger children at higher risk of hernia, the closure can still be limited to the external oblique to both prevent hernia as well as pain/nerve entrapment.
  • When performing HIR or HIDES, remember the anatomy of the iliohypogastric and ilioinguinal nerves.

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