Acute cholecystitis surgery: can doctors predict a difficult emergency operation?

Why are emergency gallbladder operations hard to plan?

Gallbladder and bile duct problems account for about one in ten emergency department presentations, and around half of those are acute cholecystitis, an inflamed and often infected gallbladder. At the first visit it can be hard to separate acute cholecystitis from biliary colic, the temporary pain of a stone blocking the gallbladder outlet.

The Tokyo Guidelines 2018 recommend early keyhole gallbladder removal for acute cholecystitis and most other acute gallbladder presentations, because early surgery is associated with fewer complications, a shorter total hospital stay and lower costs. In practice, early operations are often done after hours, and many hospitals have no standard protocol for them, so an unexpectedly difficult gallbladder can land with an on-call team that lacks the experience the operation needs.

Earlier attempts to predict difficulty relied on proxies such as operating time or conversion to open surgery, which depend heavily on the individual surgeon and hospital. This study graded what the surgeon actually saw during the operation and then looked for information available in the emergency department that predicted it.

Who was included in the study?

Adults admitted through the emergency department at Royal North Shore Hospital between July 2015 and February 2018 were included if they had keyhole gallbladder removal during the same admission or within a week of discharge. Operations were done by one of five upper gastrointestinal surgeons or by supervised trainees. Of 257 patients, 72 were excluded, mostly because their operation was delayed beyond a week, leaving 185.

On the 1 to 4 grading scale, 25 operations were Grade 1, 47 were Grade 2, 69 were Grade 3 and 44 were Grade 4, which means 113 patients (61%) had a complicated operation.

How did complicated operations differ from straightforward ones?

Patients with a complicated operation were older, more often had a positive Murphy's sign (pain and a catch in breathing when the doctor presses under the right ribs), and more often had symptoms for over 24 hours before reaching the emergency department. Their blood tests showed more inflammation, and their ultrasound more often showed a thickened gallbladder wall, fluid around the gallbladder or a stone stuck in the gallbladder neck.

Liver function tests told the opposite story. Raised liver enzymes were more common in the straightforward group, reflecting the patients with stones in the bile duct or gallstone pancreatitis, whose gallbladders were usually much less inflamed at operation.

How does the difficulty score for acute cholecystitis work?

Three findings independently predicted a complicated operation, and each was given points according to its strength. A clinical diagnosis of acute cholecystitis increased the odds about eight-fold, a CRP above 10.5 mg/L almost four-fold, and fluid around the gallbladder on imaging almost three-fold.

A total of 2.5 points or more predicts a complicated operation. As an example, a patient diagnosed with acute cholecystitis whose CRP is 40 scores 3.5, while a patient thought to have biliary colic with a CRP of 20 and fluid on the ultrasound scores 2.5. The model's accuracy, measured as the area under the curve, was 0.86.

Of patients scoring 2.5 or more, 87% had a complicated operation. Of those scoring under 2.5, 70% had a straightforward one, so a low score lowers the likelihood of a hard operation and the surgical team still prepares for one.

What did the study find about timing and severity grades?

The Tokyo Guidelines severity grade for acute cholecystitis was unrelated to how difficult the operation turned out to be, which matches several other studies. The diagnosis of acute cholecystitis mattered, and the severity grade added nothing once that was known.

The total time from the start of symptoms to surgery also made no difference, and operations done more than 72 hours after presentation were no harder than those done within 72 hours. The authors conclude that neither the severity grade nor the length of symptoms is a reason to postpone surgery beyond the first admission.

Finally, 29% of complicated operations were in patients whose working diagnosis was biliary colic only, a reminder that a gallbladder can be more inflamed at operation than the emergency assessment suggests.

What does the score change for patients with acute cholecystitis?

The score uses information already collected in every emergency department, so it takes seconds to calculate. A high score tells the team to book an experienced laparoscopic or hepatobiliary surgeon, enough theatre time and experienced nursing staff.

If a high-scoring patient arrives after hours, or the right surgeon is unavailable, the authors suggest starting with antibiotics and supportive care and operating during normal hours in the same admission. For the patient, that means the operation is planned around the people and equipment it needs while still being done early.

What are the limits of this study?

The cohort of 185 patients was relatively small, which limited how many factors could be tested together, and the score has yet to be validated in a separate group of patients. The authors call for prospective validation in another emergency population before it is used widely.