Most children with vesicoureteral reflux are asymptomatic. Vesicoureteral reflux may be diagnosed as a result of further evaluation of dilation of the kidney or ureters draining urine from the kidney while in utero as well as when a sibling has VUR (though routine testing in either circumstance is controversial). Reflux also increases risk of acute bladder and kidney infections, so testing for reflux may be performed after a child has one or more infections.

In infants, the signs and symptoms of a urinary tract infection may include only fever and lethargy, with poor appetite and sometimes foul-smelling urine, while older children typically present with discomfort or pain with urination and frequent urination.

Vesicoureteral reflux (VUR), also known as vesicoureteric reflux, is a condition in which urine flows retrograde, or backward, from the bladder into the ureters/kidneys. Urine normally travels in one direction (forward, or anterograde) from the kidneys to the bladder via the ureters, with a 1-way valve at the vesicoureteral (ureteral-bladder) junction preventing backflow. The valve is formed by oblique tunneling of the distal ureter through the wall of the bladder, creating a short length of ureter (1–2 cm) that can be compressed as the bladder fills. Reflux occurs if the ureter enters the bladder without sufficient tunneling, i.e., too "end-on".

Prenatally diagnosed hydronephrosis (fluid-filled kidneys) suggest post-natal follow-up examination.

The strongest neo-natal presentation is urinary tract infection. A hydronephrotic kidney may present as a palpable abdominal mass in the newborn, and may suggest an ectopic ureter or ureterocele.

In older children, ureteral duplication may present as:

- Urinary tract infection - most commonly due to vesicoureteral reflux (flow of urine from the bladder into the ureter, rather than vice versa).

- Urinary incontinence in females occurs in cases of ectopic ureter entering the vagina, urethra or vestibule.

Obstructive uropathy is a structural or functional hindrance of normal urine flow, sometimes leading to renal dysfunction (obstructive nephropathy).

It is a very broad term, and does not imply a location or cause.

Symptoms, less likely in chronic obstruction, are pain radiating to the T11 to T12 dermatomes, anuria, nocturia, or polyuria.

Duplicated ureter or Duplex Collecting System is a congenital condition in which the ureteric bud, the embryological origin of the ureter, splits (or arises twice), resulting in two ureters draining a single kidney. It is the most common renal abnormality, occurring in approximately 1% of the population. The additional ureter may result in a ureterocele, or an ectopic ureter.

Ectopic ureter (or ureteral ectopia) is a medical condition where the ureter, rather than terminating at the urinary bladder, terminates at a different site. In males this site is usually the urethra, in females this is usually the urethra or vagina. It can be associated with renal dysplasia, frequent urinary tract infections, and urinary incontinence (usually continuous drip incontinence). Ectopic ureters are found in 1 of every 2000–4000 patients, and can be difficult to diagnose, but are most often seen on CT scans.

Ectopic ureter is commonly a result of a duplicated renal collecting system, a duplex kidney with 2 ureters. In this case, usually one ureter drains correctly to the bladder, with the duplicated ureter presenting as ectopic.

Posterior urethral valve (PUV) disorder is an obstructive developmental anomaly in the urethra and genitourinary system of male newborns. A posterior urethral valve is an obstructing membrane in the posterior male urethra as a result of abnormal "in utero" development. It is the most common cause of bladder outlet obstruction in male newborns. The disorder varies in degree, with mild cases presenting late due to milder symptoms. More severe cases can have renal and respiratory failure from lung underdevelopment as result of low amniotic fluid volumes, requiring intensive care and close monitoring. It occurs in about one in 8000 babies.

Abdominal ultrasound is of some benefit, but not diagnostic. Features that suggest posterior urethral valves are bilateral hydronephrosis, a thickened bladder wall with thickened smooth muscle trabeculations, and bladder diverticula.

Voiding cystourethrogram (VCUG) is more specific for the diagnosis. Normal "plicae circularis" are variable in appearance and often not seen on normal VCUGs. PUV on voiding cystourethrogram is characterized by an abrupt tapering of urethral caliber near the verumontanum, with the specific level depending on the developmental variant. Vesicoureteral reflux is also seen in over 50% of cases. Very often the posterior urethra maybe dilated thus making the abrupt narrowing more obvious. the bladder wall may show trabeculations or sacculations or even diverticuli.

Diagnosis can also be made by cystoscopy, where a small camera is inserted into the urethra for direct visualization of the posteriorly positioned valve. A limitation of this technique is that posterior valve tissue is translucent and can be pushed against the wall of the urethra by inflowing irrigation fluid, making it difficult to visualize. Cystoscopy may also demonstrate the bladder changes.

Centers in Europe and Japan have also had excellent results with cystosonography, although it has not been approved for use in the United States yet.

Renal colic typically begins in the flank and often radiates to the hypochondrium (the part of the anterior abdominal wall below the costal margins) or the groin. It is typically colicky (comes in waves) due to ureteric peristalsis, but may be constant. It is often described as one of the strongest pain sensations known.

Although this condition can be very painful, kidney stones usually cause no permanent physical damage. The experience is said to be traumatizing due to pain, and the experience of passing blood, blood clots, and pieces of the stone. Depending on the sufferer's situation, nothing more than drinking significant amounts of water may be called for; in other instances, surgery may be needed. Preventive treatment can be instituted to minimize the likelihood of recurrence.

Renal colic is a type of abdominal pain commonly caused by kidney stones.

Not all patients with Schatzki rings have symptoms; barium swallow tests of the esophagus sometimes show Schatzki rings in patients with no swallowing difficulties.

When Schatzki rings cause symptoms, they usually result in episodic difficulties with swallowing (dysphagia) solid foods, or a sensation that the food "sticks" while swallowing, especially if the food is not chewed thoroughly. Patients usually are able to regurgitate or force through the food material and resume eating. However, complete obstruction of the esophagus by a bolus of food (often called steakhouse syndrome) can occur. This can cause crushing chest pain and may need immediate treatment with endoscopy, which is the use of a specialized fibre-optic camera in order to remove the lodged food. After the obstruction is located, snares or forceps are inserted to pull the food out of the esophagus or to push it into the stomach. The latter is done with caution, usually when the anatomy of the structures around the obstruction is already known.

Esophageal stricture, or narrowing of the esophagus, is usually a complication of acid reflux, most commonly due to gastroesophageal reflux (GERD). These patients are usually older and have had GERD for a long time. Esophageal stricture can also be due to other causes, such as acid reflux from Zollinger-Ellison syndrome, trauma from a nasogastric tube placement, and chronic acid exposure in patients with poor esophageal motility from scleroderma. Other non-acid related causes of peptic strictures include infectious esophagitis, ingestion of chemical irritant, pill irritation, and radiation. Peptic stricture is a progressive mechanical dysphagia, meaning patients will complain of initial intolerance to solids followed by inability to tolerate liquids. When the diameter of the stricture is less than 12 mm the patient will always have dysphagia, while dysphagia is not seen when the diameter of the stricture is above 30 mm. Symptoms relating to the underlying cause of the stricture usually will also be present.

Esophageal cancer also presents with progressive mechanical dysphagia. Patients usually come with

rapidly progressive dysphagia first with solids then with liquids, weight loss (> 10 kg), and anorexia (loss of appetite). Esophageal cancer usually affects the elderly. Esophageal cancers can be either squamous cell carcinoma or adenocarcinoma. Adenocarcinoma is the most prevalent in the US and is associated with patients with chronic GERD who have developed Barrett's esophagus (intestinal metaplasia of esophageal mucosa). Squamous cell carcinoma is more prevalent in Asia and is associated with tobacco smoking and alcohol use.

Esophageal rings and webs, are actual rings and webs of tissue that may occlude the esophageal lumen.

- "Rings" --- Also known as Schatzki rings from the discoverer, these rings are usually mucosal rings rather than muscular rings, and are located near the gastroesophageal junction at the squamo-columnar junction. Presence of multiple rings may suggest eosinophilic esophagitis. Rings cause intermittent mechanical dysphagia, meaning patients will usually present with transient discomfort and regurgitation while swallowing solids and then liquids, depending on the constriction of the ring.

- "Webs" --- Usually squamous mucosal protrusion into the esophageal lumen, especially anterior cervical esophagus behind the cricoid area. Patients are usually asymptomatic or have intermittent dysphagia. An important association of esophageal webs is to the Plummer-Vinson syndrome in iron deficiency, in which case patients will also have anemia, koilonychia, fatigue, and other symptoms of anemia.

Achalasia is an idiopathic motility disorder characterized by failure of lower esophageal sphincter (LES) relaxation as well as loss of peristalsis in the distal esophagus, which is mostly smooth muscle. Both of these features impair the ability of the esophagus to empty contents into the stomach. Patients usually complain of dysphagia to both solids and liquids. Dysphagia to liquids, in particular, is a characteristic of achalasia. Other symptoms of achalasia include regurgitation, night coughing, chest pain, weight loss, and heartburn. The combination of achalasia, adrenal insufficiency, and alacrima (lack of tear production) in children is known as the triple A (Allgrove) syndrome. In most cases the cause is unknown (idiopathic), but in some regions of the world, achalasia can also be caused by Chagas disease due to infection by "Trypanosoma cruzi".

Scleroderma is a disease characterized by atrophy and sclerosis of the gut wall, most commonly of the distal esophagus (~90%). Consequently, the lower esophageal sphincter cannot close and this can lead to severe gastroesophageal reflux disease (GERD). Patients typically present with progressive dysphagia to both solids and liquids secondary to motility problems or peptic stricture from acid reflux.

Spastic motility disorders include diffuse esophageal spasm (DES), nutcracker esophagus, hypertensive lower esophageal sphincter, and nonspecific spastic esophageal motility disorders (NEMD).

- "DES" can be caused by many factors that affect muscular or neural functions, including acid reflux, stress, hot or cold food, or carbonated drinks. Patients present with intermittent dysphagia, chest pain, or heartburn.

Rare causes of esophageal dysphagia not mentioned above

- Diverticulum

- Aberrant subclavian artery, or (dysphagia lusoria)

- Cervical osteophytes

- Enlarged aorta

- Enlarged left atrium

- Mediastinal tumor

A Schatzki ring or Schatzki–Gary ring is a narrowing of the lower esophagus that can cause difficulty swallowing (dysphagia). The narrowing is caused by a ring of mucosal tissue (which lines the esophagus) or muscular tissue. A Schatzki ring is a specific type of "esophageal ring", and Schatzki rings are further subdivided into those above the esophagus/stomach junction (A rings), and those found at the squamocolumnar junction in the lower esophagus (B rings).

Patients with Schatzki rings can develop intermittent difficulty swallowing or, more seriously, a completely blocked esophagus. The ring is named after the German-American physician Richard Schatzki.

Hiatal hernia has often been called the "great mimic" because its symptoms can resemble many disorders. Among them, a person with a hiatal hernia can experience dull pains in the chest, shortness of breath (caused by the hernia's effect on the diaphragm), heart palpitations (due to irritation of the vagus nerve), and swallowed food "balling up" and causing discomfort in the lower esophagus until it passes on to the stomach. In addition, hiatal hernias often result in heartburn but may also cause chest pain or pain with eating.

In most cases however, a hiatal hernia does not cause any symptoms. The pain and discomfort that a patient experiences is due to the reflux of gastric acid, air, or bile. While there are several causes of acid reflux, it occurs more frequently in the presence of hiatal hernia.

In newborns, the presence of Bochdalek hernia can be recognised from symptoms such as difficulty breathing fast respiration, increased heart rate.

Patients usually complain of dysphagia (the feeling of food getting stuck "several seconds" after swallowing), and will point to the suprasternal notch or behind the sternum as the site of obstruction.

The following are risk factors that can result in a hiatus hernia.

- Increased pressure within the abdomen caused by:

- Heavy lifting or bending over

- Frequent or hard coughing

- Hard sneezing

- Violent vomiting

- Straining

- Stress

Extravasation of urine due to blunt renal trauma or ureteral obstruction can lead to the formation of an urinoma.

Extravasation of urine refers to the condition where an interruption of the urethra leads to a collection of urine in other cavities, such as the scrotum or the penis in males. It can be associated with a calculus.

Pyonephrosis is sometimes a complication of kidney stones, which can be a source of persisting infection. It may also occur spontaneously. It can occur as a complication of hydronephrosis or pyelonephritis.

Signs and symptoms of acute pyelonephritis generally develop rapidly over a few hours or a day. It can cause high fever, pain on passing urine, and abdominal pain that radiates along the flank towards the back. There is often associated vomiting.

Chronic pyelonephritis causes persistent flank or abdominal pain, signs of infection (fever, unintentional weight loss, malaise, decreased appetite), lower urinary tract symptoms and blood in the urine. Chronic pyelonephritis can in addition cause fever of unknown origin. Furthermore, inflammation-related proteins can accumulate in organs and cause the condition AA amyloidosis.

Physical examination may reveal fever and tenderness at the costovertebral angle on the affected side.

Pyelonephritis that has progressed to urosepsis may be accompanied by signs of septic shock, including rapid breathing, decreased blood pressure, shivering, and occasionally delirium.

Pyonephrosis (Greek "pyon" "pus" + "nephros" "kidney") is an infection of the kidneys' collecting system. Pus collects in the renal pelvis and causes distension of the kidney. It can cause kidney failure.

A urinoma, also pararenal pseudocyst, is an encapsulated collection of extravasated urine and typically found in the area adjacent to the kidneys or to extend into the retroperitoneum.

Mallory–Weiss syndrome or gastro-esophageal laceration syndrome refers to bleeding from a laceration in the mucosa at the junction of the stomach and esophagus. This is usually caused by severe vomiting because of alcoholism or bulimia, but can be caused by any conditions which causes violent vomiting and retching such as food poisoning. The syndrome presents with hematemesis. The laceration is sometimes referred to as a "Mallory-Weiss tear".

A urinoma is the result of a breach of the integrity of the pelvis or calices of the kidney or of the ureter. The urine collection in the perirenal fat causes an inflammatory response with lipolysis resulting in its fibrous encapsulation. Urinomas are usually caused by blunt trauma to the kidneys. While extravasation of urine is common as a result a severe blunt trauma (2-18%), spontaneous resolution is typical, and urinoma formation develops only in few instances. Less common causes of urinoma development are ureteral obstructions due to cancer, calculus formation, pregnancy, or congenital causes.

Urinomas tend to develop gradually. Symptoms depend on size and location of the lesion. Eventually local pain and pressure symptoms may become apparent. Biochemical testing of renal function is indicated. Imaging (IVP, ultrasonography, CT scan) will identify the lesion. Image-guided percutaneous needle aspiration is both diagnostic and therapeutic.