Pilonidal infections

The hairs from a patient's back sometimes work their way into the skin of his natal cleft and form a sinus or fistula, just behind his anus. These sinuses are very rare indeed in Indians and Africans.

He is usually a young man who presents with an abscess in his natal cleft. A history of ''recurring abscesses at the base of his spine'' is almost diagnostic. Incising his abscess may cure him, or he may get others.

Look also for one or more openings, sometimes with hairs coming out of them, exactly in the midline 5 cm behind his anus. Often, he has another sinus, 2[nd]5 cm superiorly, and slightly to one or other side of the midline, with an indurated track joining it to the first one.

Look for hairs coming out of the sinuses. Don't mistake a pilonidal sinus for a subcutaneous or perianal fistula (22.2). If you are in doubt, remember: (1) In a pilonidal sinus there will be no induration between the lowest sinus and his anus. (2) There will be no fistulous opening inside his anus. (3) When you probe the lowest sinus, the probe will pass towards his sacrum, not his anus.

Aim to: (1) excise the sinus with a little surrounding tissue, (2) make sure that the wound heals properly, and (3) prevent hairs growing into it as it heals.

You have two choices: (1) You can do Lord's procedure (which is quite different from Lord's anal stretch). Lay open the main track, and excise the mouth of each sinus, together with a little cylinder of tissue, and then scrape, or preferably brush out, the hairs. If he will reattend regularly for postoperative care, this is probably the best method. (2) You can pass a probe through the sinus, cut down on it, and lay it open, as you would any other fistula. The most important part of the postoperative care, after either method, is to make sure that new hair does not grow into the granulating wound.

Fig. 22-12 LORD'S OPERATION FOR A PILONIDAL SINUS. Peter Lord developed two operations: (1) his anal dilatation in Figs. 22-9 and 22-10, and (2) his procedure for a pilonidal sinus shown here. A, the openings of the sinuses. B, an ellipse of skin marked out for the removal of the main sinuses. C, the ellipse being excised. D, outlying sinuses being probed. E, a haemostat being passed through the sinus. F, a little nodule of tissue being excised from the opening of the sinus. G, the sinus being brushed out. After Rob C and Smith R, ''Operative Surgery: Abdomen II', p. 777, Butterworth, with kind permission.

PILONIDAL INFECTIONS ACUTE INFECTION. Incise and drain the patient's abscess through a short incision, taking particular care to remove all hair and granulation tissue with a curette. Insert a drain. If necessary, treat his sinus later.

OPERATIVE TREATMENT [s7]FOR PILONIDAL SINUSES INDICATIONS. Two or more episodes of infection, and a persistent discharge. Be sure to operate at a time when his symptoms are quiescent.

ANAESTHESIA. You can operate on him while he is on his side, with his hips flexed, so there is no need to intubate him (A 16.12). (1) Ketamine (A 8.2). (2) As an outpatient, under local anaesthesia. Don't use subarachnoid or epidural anaesthesia[md]there is a septic lesion too close to the injection site.

METHOD. Shave the whole of his back thoroughly, especially the area near his buttocks. Put him in the left lateral position, with his buttocks over the edge of the table. Put a piece of gauze soaked in an antiseptic, such as chlorhexidine, over his anus, and towel him. Ask your asistant to stand at the other side of the table, and to retract his right buttock.

Methylene blue injection makes the tracks much more visible, especially to a beginner. Most experts reckon it is unnecessary. Insert a cannula into the sinus, and tie a purse string suture round it. Inject methylene blue while your assistant tightens the purse string.

LORD'S PROCEDURE starts with probing any side-openings to find the direction they run in. Use a No. 11 scalpel to cut round them, and remove a little cylinder of tissue about 5 mm deep, with a 4 mm disc of skin.

Clean the track you have made, if possible with a very small brush (as made for electric razors), or a small curette. Treat all side openings in the same way. When you are sure that there are no more pockets that might contain hairs, apply a gauze dressing, and don't try to pack the cavity.

Postoperatively, regular salt baths (22.1) are important. Inspect the wound from time to time to make sure it is healing from the bottom up, without bridging or fistulae. Keep his back and buttocks shaved free of hairs while his wound heals, or his sinus will recur. Eventually, the scar will become strong enough to withstand them.

LAYING OPEN is done by passing a probe or fistula director into the primary opening, and letting it emerge through any secondary openings. Or, if a track is blind, bring it out to the skin. Incise the skin between the two openings, and lay the track widely open. Remove any hairs and curette the track. If necessary, trim the wound to encourage its edges to remain widely open. Pack it with a hypochlorite, or saline dressing, and treat it as for any other granulating wound in this region (22.1).

CAUTION ! (1) Don't leave any sinuses behind. This is a disaster, and is why some surgeons excise a wedge of involved tissue down to the sacral periosteum.

Hold the raw margins of his wound apart until healing is complete. Let them heal from below, which is difficult, because of the anatomy of the natal cleft. If skin grows too soon, a residual cavity forms, into which hairs can fall or grow. Either pack the wound edges apart with a hypochlorite or saline dressing, or hold them apart by sewing a gauze roll in place. Ask him to run his finger up and down the wound itself each time he changes the dressings. This helps to keep the wound smooth and flat, removes debris, and is not painful. Give him some plastic or rubber surgeons's gloves, and some KY jelly. When he reattends, shave the edges of the wound carefully.

If he is fat, encourage him to lose weight. Ask him to separate the wound at least once a day with lateral traction. Warn him that his sinus might recur.

DIFFICULTIES [s7]WITH PILONIDAL SINUSES If his wound BLEEDS postoperatively, give him some gauze, and ask him to sit on it.

If there is EXCESSIVE GRANULATION TISSUE, curette it. Remove loose hairs.

If his skin forms a BRIDGE ACROSS THE LESION, with a dead space underneath, his sinus will recur. This is the commonest cause of recurrence, and is the result of poor operative technique, or poor postoperative care; so try to get it right next time.