OAF is a complication of oroantral communication. Other complications may arise if left untreated. For example:

- Candidal infection

- Chronic maxillary sinus infection of bacterial origin

- Osteomyelitis

- Rhinosinusitis

- Sinus pathology

Therefore, OAF should be dealt with first, before treating the complications.

Studies have shown that sinusitis is found in about 60% of the cases on the fourth day after the manifestation of sinus. Moreover, patient may be afflicted with an acute sinus disease if OAC is not treated promptly upon detecting clear signs of sinusitis. So, early diagnosis of OAC must be conducted in order to prevent OAF from setting in.

Spontaneous healing of small perforation is expected to begin about 48 hours after tooth extraction and it remains possible during the following two weeks. Patient must consult the dentist as early as possible should a large defect of more than 7mm in diameter or a dogged opening that requires closure is discovered so that appropriate and suitable treatment can be swiftly arranged or referral to Oral Maxillofacial Surgery (OMFS) be made at the local hospital, if required.

A comprehensive preoperative radiographic evaluation is a must as the risk of OAC can increase due to one or more of the following situations :-

- Close relationship between the roots of the maxillary posterior teeth and the sinus floor

- Increased divergence or dilaceration of the roots of the tooth

- Marked pneumatization of the sinus leading to a larger size

- Peri-radicular lesions involving teeth or roots in close association with the sinus floor

Hence, in such cases:

- Avoid using too much of apical pressure during tooth extraction

- Perform surgical extraction with roots sectioning

- Consider referral to OMFS at local hospital

Courses of treatment typically include the following:

- Draining the pus once awhile as it can build up a strong odor

- Antibiotics when infection occurs.

- Surgical excision is indicated with recurrent fistular infections, preferably after significant healing of the infection. In case of a persistent infection, infection drainage is performed during the excision operation. The operation is generally performed by an appropriately trained specialist surgeon e.g. an otolaryngologist or a specialist General Surgeon.

- The fistula can be excised as a cosmetic operation even though no infection appeared. The procedure is considered an elective operation in the absence of any associated complications.

Occasionally a preauricular sinus or cyst can become infected.

Most preauricular sinuses are asymptomatic, and remain untreated unless they become infected too often. Preauricular sinuses can be excised with surgery which, because of their close proximity to the facial nerve, is performed by an appropriately trained, experienced surgeon (e.g. a specialist General Surgeon, a Plastic Surgeon, an otolaryngologist (Ear, Nose, Throat surgeon) or an Oral and Maxillofacial Surgeon).

These can be both congenital or develop over time with the thinning of the otic capsule by the persistent pulsations of the intracranial pressures against the bones of the skull. Finally, disease conditions—for example cholesteatoma—can result in a labyrinthine fistula. Traumatic events, with excessive pressure changes to the inner ear such as in scuba diving, head trauma, or an extremely loud noise can lead to rupture and leakage.

When diagnosing, PLF should be differentiated from Ménière's disease. Tympanostomy has been reported to be a way to diagnose and cure PLF.

A branchial cleft cyst is a cyst in the skin of the lateral part of the neck. It can but does not necessarily have an opening to the skin surface called a fistula. The cause is usually a developmental abnormality arising in the early prenatal period, typically failure of obliteration of the second branchial cleft, i.e. failure of fusion of the second and third branchial arches. Less commonly, the cysts can develop from the first, third, or fourth clefts, and their location and the location of associated fistulas differs accordingly.

The thyroglossal tract arises from the foramen cecum at the junction of the anterior two-thirds and posterior one-third of the tongue. Any part of the tract can persist, causing a sinus, fistula or cyst. Most fistulae are acquired following rupture or incision of the infected thyroglossal cyst. A thyroglossal cyst is lined by pseudostratified, ciliated columnar epithelium while a thyroglossal fistula is lined by columnar epithelium.

Conservative (i.e. no treatment), or surgical . With surgical excision, recurrence is common, usually due to incomplete excision. Often, the tracts of the cyst will pass near important structures, such as the internal jugular vein, carotid artery, or facial nerve, making complete excision impractical.

Thyroglossal Duct Cysts are a birth defect. During embryonic development, the thyroid gland is being formed, beginning at the base of the tongue and moving towards the neck canal, known as the thyroglossal duct. Once the thyroid reaches its final position in the neck, the duct normally disappears. In some individuals, portions of the duct remain behind, leaving small pockets, known as cysts. During a person's life, these cyst pockets can fill with fluids and mucus, enlarging when infected, presenting the thyroglossal cyst.

It is often caused by childbirth (in which case it is known as an obstetric fistula), when a prolonged labor presses the unborn child tightly against the pelvis, cutting off blood flow to the vesicovaginal wall. The affected tissue may necrotize (die), leaving a hole.

Vaginal fistulas can also result from particularly violent cases of rape, especially those involving multiple rapists and/or foreign objects. Some health centers in countries such as the Democratic Republic of Congo have begun to specialize in the surgical repair of vaginal fistulas.

It can also be associated with hysterectomy, cancer operations, radiation therapy and cone biopsy.

TIF is a rare condition with a .7% frequency, and an mortality rate approaching 100% without surgical intervention. Immediate diagnosis and intervention of an TIF is critical for the surgical intervention success. 25-30% of TIF patients who reach the operating room survive. Recently, the incidence of TIF may have declined due to advances in tracheostomy tube technology and the introduction of the bedside percutaneous dilatational tracheostomy (PDT).

A salivary gland fistula (plural "fistulae") is a fistula (i.e. an abnormal, epithelial-lined tract) involving a salivary gland or duct.

Salivary gland fistulae are almost always related to the parotid gland or duct, although the submandibular gland is rarely the origin.

The fistula can communicate with the mouth (usually causing no symptoms), the paranasal sinuses (giving rhinorrhea) or the facial skin (causing saliva to drain onto the skin).

The usual cause is trauma, however salivary fistula can occur as a complication of surgery, or if the duct becomes obstructed with a calculus.

Most parotid fistulae heal by themselves within a few weeks.

Twenty to 27% of individuals with a laryngeal cleft also have a tracheoesophageal fistula and approximately 6% of individuals with a fistula also have a cleft. Other congenital anomalies commonly associated with laryngeal cleft are gastro-oesophageal reflux, tracheobronchomalacia, congenital heart defect, dextrocardia and situs inversus. Laryngeal cleft can also be a component of other genetic syndromes, including Pallister-Hall syndrome and G syndrome (Opitz-Friaz syndrome).

Neonates with TEF or esophageal atresia are unable to feed properly. Once diagnosed, prompt surgery is required to allow the food intake. Some children do experience problems following TEF surgery; they can develop dysphagia and thoracic problems. Children with TEF can also be born with other abnormalities, most commonly those described in VACTERL association - a group of anomalies which often occur together, including heart, kidney and limb deformities. 6% of babies with TEF also have a laryngeal cleft.

Vesicovaginal fistulae are typically repaired either transvaginally or laparoscopically, although patients who have had multiple transvaginal procedures sometimes attempt a final repair through a large abdominal incision, or laparotomy.

The laparoscopic (minimally invasive) approach to VVF repair has become more prevalent due to its greater visualization, higher success rate, and lower rate of complications.

Birth injuries that result in the formation of fistulas and urinary and fecal incontinence have been found to be strongly associated with economic and cultural factors. Teenagers and women who sustain injuries that develop into ureterovaginal fistulas during childbirth suffer significant social stigma. Ureterovaginal fistulas related to prolonged, obstructed labor are rare in developed nations but are more common in countries where access to emergent obstetrical care is limited.

In people with renal failure, requiring dialysis, a cimino fistula is often deliberately created in the arm by means of a short day surgery in order to permit easier withdrawal of blood for hemodialysis.

As a radical treatment for portal hypertension, surgical creation of a portacaval fistula produces an anastomosis between the hepatic portal vein and the inferior vena cava across the omental foramen (of Winslow). This spares the portal venous system from high pressure which can cause esophageal varices, caput medusae, and hemorrhoids.

The radiocephalic arteriovenous fistula (RC-AVF) is a shortcut between cephalic vein and radial artery at the wrist. It is the recommended first choice for hemodialysis access. Possible underlying causes for failure are stenosis and thrombosis especially in diabetics and those with low blood flow such as due to narrow vessels, arteriosclerosis and advanced age. Reported patency of fistulae after 1 year is about 62.5%.

The risk of the development of a lymphocele is positively correlated to the extent of the removal of lymphatic tissue during surgery (lymphadenectomy). Surgery destroys and disrupts the normal channels of lymph flow. If the injury is minor, collateral channels will transport lymph fluid, but with extensive damage, fluid may accumulate in an anatomic space resulting in a lymphocele. Typical operations leading to lymphocysts are renal transplantation and radical pelvic surgery with lymph node removal because of prostatic or gynecologic cancer. Other factors that may predispose of lymphocele development are preoperative radiation therapy, heparin prophylaxis (used to prevent deep vein thrombosis), and tumor characteristics. After radical surgery for cervical and ovarian cancer studies with follow-up CT found lymphoceles in 20% and 32%, respectively. Typically they develop within 4 months after surgery.

Surgical repair can sometimes result in complications, including:

- Stricture, due to gastric acid erosion of the shortened esophagus

- Leak of contents at the point of anastomosis

- Recurrence of fistula

- Gastro-esophageal reflux disease

- Dysphagia

- Asthma-like symptoms, such as persistent coughing/wheezing

- Recurrent chest infections

- Tracheomalacia

Low-output fistula: < 200 mL/day

Moderate-output fistula: 200-500 mL/day

High-output fistula: > 500 mL/day

Acute infectious thyroiditis is very rare, with it only accounting for about 0.1–0.7% of all thyroiditis. Large hospitals tend to only see two cases of AIT annually. For the few cases of AIT that are seen the statistics seem to show a pattern. AIT is found in children and young adults between the ages of 20 and 40. The occurrence of the disease in people between 20 and 40 is only about 8% with the other 92% being in children. Men and women are each just as likely to get the disease. If left untreated, there is a 12% mortality rate.

Treatment of a laryngeal cleft depends on the length and resulting severity of symptoms. A shallow cleft (Type I) may not require surgical intervention. Symptoms may be able to be managed by thickening the infant's feeds. If symptomatic, Type I clefts can be sutured closed or injected with filler as a temporary fix to determine if obliterating the cleft is beneficial and whether or not a more formal closure is required at a later date. Slightly longer clefts (Type II and short Type III) can be repaired endoscopically. Short type IV clefts extending to within 5 mm below the innominate artery can be repaired through the neck by splitting the trachea vertically in the midline and suturing the back layers of the esophagus and trachea closed. A long, tapered piece of rib graft can be placed between the esophageal and tracheal layers to make them rigid so the patient will not require a tracheotomy after the surgery and to decrease chances of fistula postoperatively. Long Type IV clefts extending further than 5 mm below the innominate artery cannot be reached with a vertical incision in the trachea, and therefore are best repaired through cricotracheal resection. This involves separating the trachea from the cricoid cartilage, leaving the patient intubated through the trachea, suturing each of the esophagus and the back wall of the trachea closed independently, and then reattaching the trachea to the cricoid cartilage. This prevents the need for pulmonary bypass or extracorporeal membrane oxygenation.

Surgery-associated ischemia may contribute inflammation at the anal transitional zone.

Patients whose cuffitis is refractory to mesalamine and/or corticosteroids should be evaluated for other disease in the cuff area, such as fistula or anastomotic leaks. Cuffitis that is refractory to medication can also be a sign of Crohn's disease of the pouch.

Chronic cuffitis can also contribute to the development of anastomotic stricture.

Cuffitis that is refractory, Crohn's-related, or is associated with surgical complications can contribute to pouch failure.