Three hundred and twenty two patients with pilonidal sinus disease were studied to determine factors for the development and maintenance of the disease. A calculated incidence of the disease of 26 per 100,000 inhabitants was found. It occurred 2.2 times more often in men than in women. Age at presentation was 21 years for men and 19 for women. Patients had two years (median) disease history before being referred for treatment. A family history could be found in 38% of the patients. 50% had normal body weight, and 37% were overweight. Local trauma or irritation preceded the condition in 34%, and a sedentary occupation was reported by 44%. Male sex, adolescence or youth, and a familial disposition seem to be associated with the development of pilonidal sinus. Local trauma and overweight are the most important conditioning factors for development of symptomatic pilonidal sinus disease.

This prospective study was performed to investigate epidemiological characteristics in terms of the age- and sex-specific incidence in patients with perforated and nonperforated appendicitis. The study population comprised 1486 consecutive patients who underwent appendectomy for suspected acute appendicitis between 1989 and 1993. Two patient cohorts [n = 544 (37%)] were analyzed with regard to prehospitalization duration of symptoms and in-hospital observation time. The crude incidence of acute appendicitis was 86 per 100,000 per year. Although the incidence of nonperforated appendicitis was highest among adolescents and young adults (13-40 years of age), perforated appendicitis occurred at almost the same incidence in all sex and age groups. The diagnostic accuracy was 76%. Perforated appendicitis occurred in 19%, with higher rates in small children and the elderly, irrespective of gender. A high diagnostic accuracy was not associated with an increased rate of perforation. In small children and the elderly, the diagnostic accuracy was low and the perforation rate high. Patients with perforation had a significantly longer duration of symptoms as well as in-hospital observation time than did patients with nonperforated appendicitis. Perforated appendicitis showed a different incidence pattern than nonperforated appendicitis and was associated with a significantly longer duration of symptoms and in-hospital observation time, probably due to patient-related factors. We suggest this observation deserves attention regarding clinical diagnosis and treatment decision-making for patients with suspected acute appendicitis.

Two prospective studies were undertaken to examine the role of bacteria in the outcome after excision and primary suture for chronic pilonidal sinus disease. In the first study 52 consecutive patients were given cloxacillin as prophylaxis. In a second randomised study 51 patients were given 2 g cefoxitin intravenously (n = 25) or no prophylaxis (n = 26). From 49 out of 98 patients (50%) no microorganisms were isolated from sinuses preoperatively. Wound complications were observed postoperatively in 61% of the patients (63/103). A postoperative bacteriology sample was positive in 47 of 49 samples (96%). Preoperative presence of bacteria was not significantly associated with wound complications. Anaerobe isolates were present in 40% of patients preoperatively whereas aerobes were cultured in 43% postoperatively. After an observation period of 30-42 months, recurrences were 13% among the patients (7/52) who had been given cloxacillin. No recurrences were seen in the last study after an observation period of 18-30 months, for an overall 7% in both studies. We conclude that preoperative bacterial isolates, usually anaerobes, in chronic pilonidal sinuses do not influence the complication rate since bacterial isolates from infected wounds are mostly aerobes.

In this population-based study, diagnostic accuracy in patients operated on for suspected acute appendicitis increased for all patients when structured preoperative data collection was used. However, the only subgroup with a significant increase in diagnostic accuracy was female patients aged between 13 and 40 years. Perforation rate was unaffected by structured data collection.

A clinical and histologic study of recurrent pilonidal sinus is presented. During a 5-year period 44 patients were treated for recurrent pilonidal sinus. Of these, recurrence had occurred within 1 year in 26 patients (76%). After 26 reoperations with excision and primary suture further recurrence was seen in 23% (6/26), and in 24% (6/25) after reoperations with open treatment. The histologic findings in recurrent sinuses (18 patients) were almost identical to that of primary disease. Recurrent sinuses were situated in the scar in 80% of the cases and caudal in 50% of the cases. A known wound infection had been present in 27% of the patients. Although keratin plugs were observed in 15/18 (83%) of those with a recurrence, the importance of this finding is uncertain. We conclude that recurrent pilonidal sinuses are chronic inflammatory processes usually located at the site of the surgical wound. The cause is uncertain, although there is an indication that wound infection plays a role. Keratin plugs have also been observed in scar tissue. Surgical treatment of recurrent disease has a higher recurrence rate than after that of primary disease.