Final answer:
The 16-year-old female presenting with severe lower quadrant pain and rebound tenderness likely has appendicitis, a condition requiring prompt medical treatment. Appendicitis is indicated by her symptoms, which are also common among sexually active females, and her pain is located in the typical area for this condition.
Step-by-step explanation:
The patient is a 16-year-old female presenting with severe lower quadrant abdominal pain and noting sexual activity. Her symptoms include rebound tenderness in the right lower quadrant, a classic sign of appendicitis. Rebound tenderness, when the pain gets worse after pressure is removed from the abdomen, is commonly associated with appendicitis, which is an infection of the appendix causing inflammation. Infections can escalate, making appendicitis a medical emergency when not treated promptly.
An ectopic pregnancy is another possible concern for sexually active females with abdominal pain, involving a pregnancy that occurs outside the uterus, most often in the fallopian tubes. However, this condition typically occurs with additional symptoms such as vaginal bleeding and often presents slightly later than three weeks after the last menstrual period.
Renal colic, associated with kidney stones, could cause severe pain and is often accompanied by nausea, vomiting, or hematuria. However, this condition tends to cause pain that radiates to the flank or back.
Cholecystitis, inflammation of the gallbladder often due to gallstones, would more typically cause pain in the right upper quadrant, not the lower quadrant.
Considering the patient's sexual activity, location of pain, and presence of rebound tenderness, appendicitis seems to be the most likely diagnosis. However, it's important for healthcare providers to consider all potential conditions and possibly conduct further diagnostic testing to confirm the diagnosis.