RD = Rinichi Drept
RK = Right Kidney
Calcul (Ro) = Calculus (En), plural Calculi
If there is a "microcalcul" in Romanian, it will be "microcalculus" in En.

Here is the logical conclusion, with references in Romanian and English:
http://www.gabimatei.ro/operatie-colecist/
“CAND ESTE INDICATA INTERVENTIA CHIRURGICALA?
Interventia chirurgicala este necesara in cazul diagnosticarii (ecografice) a litiazei colecistice (pietre sau calculi), colecistitele acute litiazice si alitiazice (inflamatii ale colecistului din alte cauze decat cea litiazica – achene colesterolotice, polipi), traumatismele spontane, cancerul de colecist.”
“ In plus, datorita marimii calculului si a faptului ca sunt supraponderal si hipertensiv mi s-a spus ca o operatie laparoscopica este putin probabila.”
http://www.sfatulmedicului.ro/Afectiuni-ale-rinichilor/ce-tr...
“Ce trebuie sa stii despre pietrele la rinichi (calculi renali)”
http://medlive.hotnews.ro/putem-scapa-de-durerea-produsa-de-...
“se impune analiza chimica a calculilor eliminati sau operatie pt a evalua anomalia metabolica cauzala. Exista posibilitatea in unele situatii de a aplica un tratament medicamentos care sa dizolve in timp calculii, cum ar fi calculii de acid uric, dar si situatia unor anomalii metabolice ce permit corectia medicamentoasa si in acest fel profilaxia litiazei de aparat urinar. regula de baza insa pentru a impiedieca formarea calculilor in rinichi ramane cura de diureza, respectiv ingestia a cel putin 2,5-3 litri de lichid in 24 de ore, inclusiv cu acoperirea intervalului nocturn, cand exista un risc mai mare de formare a calculilor.”
http://emedicine.medscape.com/article/437096-overview
“Nephrolithiasis specifically refers to calculi in the kidneys, but renal calculi and ureteral calculi (ureterolithiasis) are often discussed in conjunction. The majority of RENAL CALCULI contain calcium. The pain generated by renal colic is primarily caused by dilation, stretching, and spasm because of the acute ureteral obstruction.”
https://en.wikipedia.org/wiki/Calculus_(medicine)
“A calculus (plural calculi), often called a stone, is aconcretion of material, usually mineral salts, that forms in an organ or duct of the body. Formation of calculi is known as lithiasis (/ˌlɪˈθaɪəsɨs/). Stones can cause a number of medical conditions.”
http://www.allacronyms.com/_medical/RK/Right_Kidney
“RK means Right Kidney”


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Note added at 2 days16 hrs (2015-11-29 07:18:44 GMT)
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https://books.google.co.uk/books?id=MOldOnhu2QUC&pg=PA89&dq=...
https://books.google.co.uk/books?id=IKTFFKMHVJEC&q=Right Kid...

RK = Right Kidney