Predictive Factors for Unanticipated Admissions After Ambulatory Laparoscopic Cholecystectomy FREE

OUTPATIENT laparoscopic cholecystectomy was first reported by Reddick and Olsen¹ in 1990. With mounting pressure to contain costs and the use of hospital beds, the proportion of laparoscopic cholecystectomies performed in the ambulatory setting has been growing rapidly. Ambulatory laparoscopic cholecystectomy has now become an established practice for the management of gallstone disease in our institution.

Unanticipated admission after ambulatory laparoscopic cholecystectomy disrupts the smooth management of ambulatory and inpatient services. Hasty arrangement for the admission is stressful to the patients, their relatives, and the surgeon. The unanticipated admission rate therefore represents a quality index that measures the success of ambulatory laparoscopic cholecystectomy.^{2 - 3} The present study was conducted to analyze the causes of unplanned admission. Multivariate analyses of clinicopathologic factors were performed to identify independent predictive factors for admission after ambulatory laparoscopic cholecystectomies. These results can allow early identification of patients at increased risk for admission and offer guidance in future selection of patients for ambulatory laparoscopic cholecystectomies.

Between January 1, 1996, and December 31, 1999, 731 ambulatory laparoscopic cholecystectomies were performed at the Department of Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Mass. Patients who were admitted after ambulatory laparoscopic cholecystectomies were identified retrospectively. For each case resulting in admission, 4 control patients who were discharged successfully on the day of operation were randomly selected during the study period. A review of the patients' medical records was performed to document demographic features, results of preoperative biochemical and hematologic studies, ultrasonographic findings, details of the operation, and pathological findings.

The selection criteria for patients undergoing ambulatory laparoscopic cholecystectomies included American Society of Anesthesiologists risk classification I or II, absence of adverse history with anesthesia, anticipated operation time of less than 90 minutes, informed consent to day surgery by the patient, and the availability of a competent adult to accompany the patient home and look after the patient for 24 hours.

All patients were admitted on the day of operation after a midnight fast. The procedures were usually scheduled in the morning session of the operation list. All patients underwent laparoscopic cholecystectomies using a standard 4-port technique, with the patient under general anesthesia. Local infiltration of the wounds with 10 mL of 0.5% bupivacaine hydrochloride was routinely performed before skin incisions.

After assessment by the operating surgeon, the patients were discharged from the day surgery unit in the afternoon when their clinical conditions had satisfied the following discharge criteria⁴ : alert and oriented to time and place; stable vital signs for at least half an hour; pain controllable by oral analgesics; no emesis (mild nausea if any present); no bleeding from the operative site; able to void; able to retain oral fluids; able to walk without dizziness; discharge instructions from surgeon and anesthesiologist and prescriptions provided; and adult present to accompany patient home.

All patients were given a supply of compound tablets, a combination of acetaminophen, 325 mg, and oxycodone hydrochloride, 5 mg, for analgesia. Patients were scheduled to follow up at the general surgical clinic 2 to 3 weeks after operation.

Statistical comparisons of 19 clinicopathologic factors between the case and control groups were performed by means of the t and χ² tests where appropriate. Clinical factors (n = 16) studied included age; sex; body weight; American Society of Anesthesiologists risk classification; employment status; preoperative white blood cell count; levels of hemoglobin, hematocrit, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and bilirubin; preoperative ultrasonographic findings of thickened gallbladder wall and contracted gallbladder; operative duration; and time of completion of surgery (before vs after 3 PM). Pathological variables (n = 3) evaluated included gallbladder wall thickness, cystic duct diameter, and maximum diameter of the gallstone. Significant variables associated with unplanned admission were then chosen for multivariate analyses by means of multiple logistic regression models using a stepwise approach to identify independent predictive factors for unanticipated admission. A P<.05 was regarded as significant. Statistical analysis was performed using a commercially available software program (Statistical Package for the Social Sciences; SPSS Inc, Chicago, Ill).

Of the 731 consecutive outpatient laparoscopic cholecystectomies completed without conversion, the mean (± SD) age of the overall population was 41.0 ± 12.6 years. There were no hospital mortalities. Twenty-five patients required admission after operation, leading to an overall unplanned admission rate of 3.4%. The reasons for admission were pain (n = 10), nausea and vomiting (n = 6), pain with urinary retention (n = 3), patient preference (n = 3), urinary retention (n = 2), and medical observation (n = 1) (Figure 1).

By univariate analysis, length of operation, thickened gallbladder wall on ultrasonographic and pathological findings were significantly associated with unplanned admission (Table 1). Nineteen and 36 patients in the case and control groups, respectively, had operations exceeding 60 minutes (P = .001). The relative risks for unanticipated admission for the ultrasonographic finding of a thickened gallbladder wall and an operation exceeding 60 minutes were 3.63 and 4.03, respectively. By logistic regression analysis, length of operation was the only independent predictive factor for unplanned admission (P = .007; 95% confidence interval, 1.02-1.12).

In the case group (n = 25), 23 patients (92.0%) were discharged the next day, and 2 stayed for 2 nights. All but 1 patient had uneventful recoveries. That patient was readmitted on postoperative day 3 because of increasing abdominal pain. Results of contrast-enhanced computed tomography revealed a hepatic subcapsular hematoma. Expectant treatment was adopted after an exploratory laparoscopy confirming the diagnosis. The hepatic hematoma gradually resolved during follow-up. In the control group (n = 100), there were 2 readmissions to hospital because of bile leakage (n = 1) and retained common bile duct stone (n = 1).

Operative records of the case group were reviewed to search for reasons of prolonged operation. Concomitant procedures included intraoperative cholangiography (n = 2), umbilical hernia repair (n = 2), and attempted cholangiography (n = 1). Operative difficulties were recorded in 18 patients. These included 1 or more of the following reasons: adhesions (n = 13), thickened gallbladder wall with chronic inflammation (n = 4), gallbladder perforation (n = 3), redundant hepatic caudate lobe obscuring view (n = 1), impacted gallstone at gallbladder neck (n = 1), and obesity with friable gallbladder (n = 1).

Our unplanned admission rate of 3.4% after ambulatory laparoscopic cholecystectomies compares favorably with the results of other centers, which ranged from 1% to 39%.^{5 - 13} A lower admission rate has been reported in freestanding ambulatory surgery centers, but this could be related to their strict patient selection criteria. Results should therefore be compared among similar health care settings.^{2 ,14}

More than half of our patients were admitted because of uncontrolled postoperative pain. Pain was the principal reason for admission in 2 large series of ambulatory surgery, which recruited more than 20 000 patients.^{2 - 3} Although adequate analgesia is the primary concern of postoperative care, adverse effects of narcotic use, such as nausea and retention of urine, cannot be neglected. Nausea and vomiting accounted for one quarter of our unplanned admissions. To achieve optimal analgesia and minimal adverse effects, a multimodal method using a combination of opioids, nonsteroidal anti-inflammatory drugs, and local anesthesia had been adopted since the inception of the ambulatory laparoscopic cholecystectomy service. Research on further improvement of pain and antiemetic treatment after ambulatory laparoscopic cholecystectomy is therefore essential.

Admission is usually a joint decision made by the surgeon and the patient. As patients have to participate in self-care after discharge, their comfort, preference, and safety need to be considered on the assessment for discharge.¹⁵ The aim of admission after ambulatory surgery is chiefly to allow management of short-term problems, namely pain, nausea, vomiting, and retention of urine. With appropriate selection of patients, few should be admitted for medical observation. More than 90% of our admitted patients were discharged the next day once their ailments resolved.

In the present study, patients with postoperative complications in the case and control groups were all readmitted subsequently. Admission of the patient had no impact on the course of postoperative complication.^{16 - 17} As postoperative morbidity usually manifests after 24 hours, most complications will not be detected during a 1-day admission.^{16 ,18} However, Saunders et al¹⁷ have attributed mortality to early discharge of patients after laparoscopic cholecystectomy.¹⁷ In their report, the patient, who was an elderly woman with mild dementia, died of bowel perforation at home on postoperative day 4. This report illustrated the importance of careful selection of patients for ambulatory laparoscopic cholecystectomy. In selected healthy patients, concern for delay in instituting treatment of complications owing to early discharge does not seem to be justified.

Operative duration of 60 minutes or longer was the most important predictor of unanticipated admission.^{2 ,6 ,19} The length of operative procedure is a multifactorial function, including the number of concomitant procedures, occurrence of intraoperative complications, etc. In the setting of a major teaching hospital, training of surgical residents is mandatory, and most ambulatory laparoscopic cholecystectomies are performed by surgical residents under supervision. Performance of the whole procedure by an experienced surgeon will definitely reduce the length of operation. For the sake of the patient, it is therefore the responsibility of the attending surgeon to ensure that the operation is performed in a timely fashion. Prolonged operation could also be due to unexpected abnormalities or a more extensive disease process than originally expected.^{3 ,14} Adhesions and thickened gallbladder wall were the 2 most common technical difficulties encountered in the case group. Inadvertent perforation of gallbladder with leakage of gallstones will also inevitably prolong the procedure. Unfortunately, all these factors except the demonstration of gallbladder wall thickening are virtually unpredictable by means of ultrasonography before the operation. Factors influencing the operative duration of laparoscopic cholecystectomy can be identified only by future prospective studies.

The unanticipated admission rate may reflect deficiencies in patient selection criteria. Patients with a thickened gallbladder wall on preoperative ultrasonographic findings have a 3-fold increased risk for admission, compared with those with normal thickness of the gallbladder wall. Corr et al²⁰ reported a significant association of gallbladder wall thickening and technical difficulty of operation. Ultrasonography is a valuable preoperative assessment tool, and the demonstration of a thickened gallbladder wall should be taken into consideration in scheduling an ambulatory laparoscopic cholecystectomy. All at-risk patients should be scheduled appropriately to optimally manage resources. An operation that goes beyond its scheduled time not only increases the risk for admission but also delays subsequent procedures. On the other hand, careful physical examination to exclude the presence of an inconspicuous paraumbilical hernia can help to avoid unexpected hernia repair. The success of day surgery relies on careful patient selection, skillful operative techniques, safe anesthesia, and adequate postoperative care.²¹

Length of operation was the only independent predictive factor for unplanned admission. An operation exceeding an hour incurred a 4-fold increased risk for admission. Ultrasonographic findings of gallbladder wall thickness should be incorporated into the selection criteria of patients for ambulatory laparoscopic cholecystectomy.

Corresponding author and reprints: David C. Brooks, MD, Department of Surgery, Brigham and Women's Hospital, Harvard Medical School, 75 Francis St, Boston, MA 02115 (e-mail: dcbrooks@bics.bwh.harvard.edu).